Multi-Colored Lustrous Pearlescent Pigments and Process for Making

ABSTRACT

A pearlescent pigment comprising a substrate and a first layer, wherein the first layer comprises iron oxide, wherein the iron has from about 1% to about 30% Fe(II) and from about 70% to about 99% Fe(III). A process for making these pearlescent pigment, comprise reducing a metal oxide substrate with a hydrogen source in the presence of a noble metal catalyst in a liquid medium. The pigments may be used in a variety of applications including cosmetics, plastics, automotive, or architectural coatings.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application hereby claims the benefit of the non-provisionalpatent application Ser. No. 11/765,614, filed on Jun. 20, 2007, and theprovisional patent application Ser. No. 60/865,042, filed on Nov. 9,2006, the disclosures of which are hereby incorporated by reference intheir entirety.

BACKGROUND OF THE INVENTION

The present invention relates, in general, to multi-colored lustrouspearlescent pigments.

Along with gem stones (e.g., diamond, ruby, emerald, topaz, opal, jade),and precious metals (e.g., gold, silver, platinum), pearls are among themost prized possessions (or luxury items) for human beings formillenniums. Beside their natural beauty, the brilliant color andluster, they are often associated with social status and level ofwell-being. As a result, and not surprisingly, the trend of cosmeticsmakeup is to emulate or recreate these “natural” and “aesthetic”appearances of pearl, gem and precious metals with less expensivematerials such as interference pigments (e.g., metal oxide coated mica).The most common types of pearlescent pigments are micronized titaniumdioxide, metal oxide coated mica, metal oxide coated alumina, metaloxide coated silica, basic lead carbonate, bismuth oxychloride, andnatural fish silver.

Metal oxide coated mica pigments are characterized by excellent optical,chemical, mechanical, toxicological, and environmental properties.Natural or synthetic mica, and alternative supports, such as aluminumflakes, or SiO₂ platelets, can be used alone, or as a support fortitanium dioxide, iron oxide (Fe₂O₃ or Fe₃O₄), iron ferrocyanide (IronBlue or Prussian Blue), tin oxide, and chromium oxide. The color spacedefined by these coated mica-based pigments is based on the type ofcoating (e.g. metal oxide, colorant, etc.) used, the layer thickness,and the number of coated layers.

Among the natural pearls, the most expensive are black pearls, whichcome with various undertone and color flops. To faithfully emulate thisaesthetic optical effect in cosmetic makeup is one of the top challengesfacing a cosmetic pigment maker and formulator. The traditional approachto these pigments is to blend dark solid-color inorganic pigment (e.g.,carbon black) with white platy pearlescent pigments (e.g., TiO₂ coatedmica, TiO₂ coated borosilicate, TiO₂ coated alumina). The platyinterference pigment provides the luster, brilliance (reflection),transparency and depth of field. The solid-color pigment(s) provide(s)the dark undertone and surface coverage. However, this type of blendusually appears to be much “dirtier”, “lack luster”, and “lacktransparency” compared to the natural pearl. The primary reason for thatis fouling of the smooth surface of white pearlescent pigment by thesolid-color pigment granules, which leads to light scattering anddisruption of light interference.

Metal oxide coated platelet pigments may be magnetic or exhibit magneticsusceptibility. When placed into a liquid coating, regions of the coatedpigment may be aligned by an externally applied magnetic field andproduce a goniochromatic, or angle dependent optical effect. This effectmay be used to create an impression of a two- or three-dimensionalimage. After the pigments have been aligned, the coating may be cured tosolidify the optical effect. Examples of pigments and methods ofaligning them are discussed in U.S. Pat. No. 6,589,331, U.S. Pat. No.6,902,807, U.S. Pat. No. 5,223,360, U.S. Pat. No. 6,759,097, and U.S.Pat. No. 7,258,900. However, the magnetic pigments are significantlylimited in terms of color space. The typical colors available aremetallic black, grey shades, or bichromic shades characterized by ablack or reddish brown absorbance color combined with a weakinterference color.

A need exists to expand the existing color space of metal oxide coatedpigments to more vibrant, lustrous colored shades, as well as, antiquedark pearlescent shades, using a processing method that allows foroptimal control of color and opacity. In addition, a need exists formore colorful magnetic pigments that have a larger color contrastbetween aligned and non-aligned pigments.

BRIEF SUMMARY OF THE INVENTION

The invention overcomes the above-noted and other deficiencies of theprior art by providing a pearlescent pigment comprising a substrate anda first layer, wherein the first layer comprises iron oxide, wherein theiron in the iron oxide comprises from about 10% to about 20% Fe(II), andfrom about 80% to about 90% Fe(III).

Another aspect of the invention is a pearlescent pigment, wherein thepigment is an inorganic material and the color of a homogeneous coatingof the pigment, measured over a white background, is selected from thegroup consisting of: a CIELAB hue angle, h_(ab), from about 50 to about80 degrees, wherein L* is not more than about 85, and the chroma valueis greater than 22; a CIELAB hue angle, h_(ab), from about 80 to about275 degrees, wherein L* is not more than about 80, and the chroma valueis greater than about 10; and a CIELAB hue angle, h_(ab), from not lessthan about 275 to not more than about 50 degrees, wherein L* is not morethan about 85, and the chroma value is greater than about 9.

Another aspect of the invention is a pearlescent pigment, wherein thepearlescent pigment is an inorganic material and the color of ahomogeneous coating of the pigment, measured over a white background,has a CIELAB L* value of about 30 or less and a chroma value of about 3or less.

Another aspect of the invention is a pearlescent pigment, wherein thepigment is prepared by coating a substrate with a metal oxide to form afirst layer, and reducing the metal oxide of the first layer, whereinonly about 10% to about 20% of the metal is reduced.

Another aspect of the invention is a pearlescent pigment, wherein thehomogeneous pearlescent pigment is an inorganic material and the ΔE*between the magnetically aligned and non aligned pigment as measuredover a white background is not less than 20.

Another aspect of the invention is a process for reducing a metal oxidecoated substrate with a hydrogen source in the presence of a noble metalcatalyst.

Another aspect of the invention is a process for making a pearlescentpigment, comprising reducing an iron oxide coated substrate with ahydrogen source, wherein only about 1% to about 30% of the iron isreduced.

Another aspect of the invention is a highly active catalyst, comprisinga nanoparticulate noble metal in a polyvinylpyrrolidone (PVP) polymer,or other polymer.

Another aspect of the invention is a cosmetic formulation containing apearlescent pigment comprising a substrate and a first layer, whereinthe first layer comprises iron oxide, wherein the iron in the iron oxidecomprises from about 10% to about 20% Fe(II), and from about 80% toabout 90% Fe(III).

Another aspect of the invention is a cosmetic composition containing apearlescent pigment comprising a substrate and a first layer, whereinthe first layer contains iron oxide, wherein the iron of the iron oxidehas from about 1% to about 30% Fe(II) and from about 70% to about 99%Fe(III).

Another aspect of the invention is a paint or ink composition containinga pearlescent pigment comprising a substrate and a first layer, whereinthe first layer comprises iron oxide, wherein the iron of the iron oxidehas from about 1% to about 30% Fe(II) and from about 70% to about 99%Fe(III).

Another aspect of the invention is a plastic composition containing apearlescent pigment comprising a substrate and a first layer, whereinthe first layer comprises iron oxide, wherein the iron of the iron oxidehas from about 1% to about 30% Fe(II) and from about 70% to about 99%Fe(III).

These and other objects and advantages of the present invention shall bemade apparent from the accompanying drawings and the descriptionthereof.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a graph of the CIELAB a* and b* color coordinates of Examples14-16 as measured against a black background.

FIG. 2 is the visible spectra of the filtrates of the pigments tested inExample 18.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to lustrous, pearlescent pigments withcontrolled opacity, comprising a substrate and a first layer, whereinthe first layer comprises iron oxide, wherein the iron in the iron oxidecomprises from about 1% to about 30% Fe(II) and from about 70% to about99% Fe(III).

Iron oxide coated substrates exhibit intensely colored pearlescentpigments with high luster. Varying the substrate, the iron oxide layerthickness, and the amount of Fe(II) and Fe(III) in the layer will changethe color, luminosity, and transparency of the pigment. The meanthickness of the first layer may be from about 1 nm to about 350 nm,from about 10 nm to about 350 nm, or from about 10 nm to about 250 nm.

In one embodiment, the pigment may comprise a second layer locatedbetween the substrate and the first layer, wherein the second layer hasa refractive index of greater than about 1.6 or less than about 1.4. Thesecond layer may have a refractive index equal to or greater than about1.8. Examples of compounds that may be used as the second layer are:TiO₂, Fe₂O₃, ZrO₂, SnO₂, Cr₂O₃, BiOCl, and ZnO. The second layer maycomprise one or more materials. The second layer may be TiO₂. The secondlayer may be an iron oxide, such as Fe₂O₃, Fe₃O₄, FeOOH, FeO, andFe(OH)₃. The mean thickness of the second layer may be from about 50 nmto about 800 nm, or from about 100 nm to about 600 nm.

In another embodiment, titanium oxide coated mica pigments exhibitpearlescent effects resulting from reflection and light interference.The interference color and luster is dependent on the thickness of theTiO₂ surface layer and its corresponding surface roughness. This initialinterference color of the pigment, prior to the coating of the firstlayer is apparent when viewed against a black background. It has beensurprisingly discovered that FeOOH deposition followed by reductionresults in the advancement of the interference color and a significantincrease in opacity of TiO₂ coated platelet-like pigments. This processtransforms the transparent, TiO₂ coated mica, into a lustrous coloredpearlescent pigment with increased opacity. The thickness of thedeposited FeOOH layer controls the magnitude of the color progressionand opacity. For relatively thick FeOOH layers, the interference colorprogresses to the next shade and the pigment approaches completeopacity.

In order to improve the light, water repellency, weather stability,texture, and dispersion ability, it is frequently advisable to subjectthe finished pigment to surface treatment, depending on the area ofapplication. Examples of surface treatments are methicone(poly(oxy(methylsilylene))), metal soap, fatty acid, hydrogenatedlecithin, dimethicone (polydimethylsiloxane), fluorinated compounds,amino acids, N-acylamino acids, glyceryl rosinates, silanes, andcombinations. Many of the processes are described in U.S. Pat. No.6,790,452; U.S. Pat. No. 5,368,639; U.S. Pat. No. 5,326,392; U.S. Pat.No. 5,486,631; U.S. Pat. No. 4,606,914; U.S. Pat. No. 4,622,074; GermanPatent 22 15 191; DE-A 31 51 354; DE-A 32 35 017; DE-A 33 34 598; DE 4030 727 A1; EP 0 649 886 A2; WO 97/29059; WO 99/57204; U.S. Pat. No.5,759,255; EP 0090259; EP 0 634 459; WO 99/57204; WO 96/32446; WO99/57204; U.S. Pat. No. 5,759,255; U.S. Pat. No. 5,571,851; WO 01/92425;U.S. Pat. No. 5,472,491; J. J. Ponjee, Philips Technical Review, Vol.44, No. 3, 81 ff; and P. H. Harding J. C. Berg, J. Adhesion Sci.Technol. Vol. 11 No. 4, pp. 471-493. This post-coating may furtherincrease the chemical stability or simplify handling of the pigment, inparticular incorporation into various media. In order to improve thewettability, dispersibility and/or compatibility with the user media,functional coatings of Al₂O₃ or ZrO₂ or mixtures thereof may be appliedto the pigment surface.

In one embodiment, coupling agents may be used to form an outer layer onthe pearlescent pigment. Suitable coupling agents are disclosed in EP632 109. Examples include, silanes, zirconium aluminates, zirconates,and titanates. The silanes may possess the structure Y—(CH₂)_(n)—SiX₃ inwhich n is 2-8, Y is an organofunctional group, e.g. an amino,methacrylic, vinyl, alkyl, aryl, halogen and/or epoxy group, and X is asilicon-functional group which following its hydrolysis reacts withactive sites of an inorganic substrate or by condensation with othersilicon compounds. This group Y may comprise, for example a hydroxy, ahalogen or an alkoxy group.

In addition to these substantially hydrophilic coupling agents, it isalso possible to use hydrophilic silanes, especially the aryl-, alkyl-and fluoroalkyl-substituted di- and trimethoxysilanes. These include,for example, phenethyltrimethoxysilane, propyltrimethoxysilane,butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane,octyltrimethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyltrimethoxysilane and(3,3,3-trifluoropropyl)methyldimethoxysilane. The concentration ofcoupling agents may be 0.2-1.2% by weight with respect to the basepigment.

In one embodiment, the substrate is platelet-like and may have a meanthickness of about 0.05 to about 1.5 μm and a mean width of about 1 toabout 750 μm. The substrate may have a mean width of about 10 to about60 μm, about 5 to about 25 μm, about 10 to about 100 μm, about 40 toabout 250 μm, or about 95 to about 730 μm.

As an example, when a relatively thin FeOOH coating on an iridescentblue TiO₂ coated laminar substrate (such as SunPearl Iridescent Blue bySunChemical) is reduced by hydrogenation, a semi-opaque lustrousblue-green or turquoise pearlescent pigment results (see Example 26).However, using this same iridescent blue substrate a thicker FeOOHcoating will result in a lustrous green or olive pearlescent shade withincreased opacity when reduced using similar hydrogenation conditions(see Example 27). This color advancement trend is applicable to manyshades of TiO₂ coated laminar substrates. Therefore, more opaque bluepearlescent shades may be produced by reduction of iridescent violetTiO₂ coated substrates (such as SunPearl Iridescent Violet bySunChemical) containing thick FeOOH coatings (see Example 23). Likewise,less opaque green shades may be produced by reduction of iridescentgreen TiO₂ coated substrates (such as SunPearl Iridescent Green bySunChemical) having relatively thin FeOOH surface layers (see Example8).

The synthesis of a particular colored pearlescent pigment begins withselection of the proper substrate material. The substrate may becomprised of natural mica, synthetic mica, glass flakes, Al₂O₃platelets, SiO₂ platelets, BiOCl, borosilicate, synthetic alumina, andboron nitride. Such substrates may be multilayer materials, i.e. includematerials of different refractive indices. The substrate may comprisemica. The pearlescent pigment may comprise a mixture of differentsubstrates. Furthermore, the substrate may be made of identical ordifferent flakes which differ in particle size.

The first step in forming a colored pearlescent pigment is to coat thesubstrate, or metal oxide coated substrate with a layer of non-annealedFeOOH, which is usually pale yellow in color. For the reasons ofdecreased crystallinity and higher surface area (porous microstructure),non-annealed FeOOH may be reduced to an iron oxide (FeO, FeO—Fe₂O₃,Fe₃O₄) under more mild reaction conditions, as compared to the morecrystalline Fe₂O₃. The methods of deposition (or precipitation) of FeOOHor Fe(OH)₃ onto substrates are well known in the literature, for exampleas shown in Dyes and Pigments, 58 (2003), 239-244, U.S. Pat. No.3,926,659, and in many scientific papers and patents particularly byMerck, Engelhard, and BASF. It is possible to start from a pre-coatedsubstrate and coat this substrate with a metal oxide. Alternatively, theprocess may start from the substrate itself and a single coating may beused to reach the correct amount of iron oxide. Metal oxides other thanFeOOH may used to the coat the substrate, or metal oxide coatedsubstrate.

The basic principle of deposition is as follows: Fe³⁺ precursors such asferric chloride, ferric sulfate, or both, are dissolved in an acidicmedium containing the substrate. As the pH is increased by the additionof bases such KOH, NaOH, LiOH, and ammonia; Fe³⁺ ions are precipitatedout as either colloidal FeOOH particles, or dense aggregates dependingon the pH control profile, temperature and concentration, and in somecase the presence of electrical field. In the presence of substrateswith affinity to FeOOH, the colloidal particles can quickly form auniform film on the substrate. The bonding between the deposited layerand substrate is usually a combination of metal oxide covalent bonds andhydrogen bonds. For example, in the case of making an antique burgundypearlescent pigment, the substrate is hematite (red calcined Fe₂O₃)coated mica, which has extremely good affinity to FeOOH.

The traditional precipitation process utilizing KOH and NaOH is called aheterogeneous hydrolysis process. However, more recently, a newerprocess called homogenous hydrolysis, utilizes urea as an in situgenerated base. This process is said to produce a smoother and moretransparent metal oxide film as shown in Dyes and Pigments 58 (2003)239-244, and Materials Research Bulletin (1999), vol. 34, no. 6,905-914. The use of ferric sulfate may produce coarser particles, andweaker luster than ferric chloride. A computer-programmed rate-controlheater may be used to better control the decomposition rate of urea,which in turn controls the rate of ammonia (base) generation. When thebase generation rate is zero order (i.e., constant), the FeOOH colloidswill nucleate and grow at a constant rate, and precipitate onto thesubstrate at a constant rate as well. As a result, a highly uniform filmcan be generated. At 80° C.-90° C., the urea hydrolysis is nearly zeroorder. This temperature range may be useful as the plateau (holding)temperature of the process. The amount of urea used is just enough tobring the final hydrolyzed solution pH to be between 6 and 8, in orderto minimize the amount of free Fe³⁺ precursor left in the solution. Fe³⁺is known to be at its lowest solubility around pH 8.

Depositing FeOOH by the Fe(III)-urea homogeneous hydrolysis may lead touniform layers of FeOOH on the surface of the titanium dioxide coatedmica substrates, which results in neon shaded pearlescent pigments (neongreen-gold, neon pink, neon silver gold, etc.) that are not currentlyavailable commercially.

After deposition of a thin layer of FeOOH onto the colored substrate,the pigments are recovered from the solution by filtration. The pigmentsare washed multiple times with deionized water to remove residual urea,followed by drying to remove residual moisture. Following sufficientdrying, the dry pigments are ready for reduction. Hydrogenation may beused to reduce the FeOOH layer. The resultant iron oxide (FeO,FeO—Fe₂O₃, Fe₃O₄) layer is typically darker in color, depending on thedegree of reduction, thickness of the layer, and any other layers.Generally speaking, the more aggressive the hydrogenation conditions orthe thicker the layer, the darker the final pigment will be. However, anoverly thick iron oxide (FeO, FeO—Fe₂O₃, Fe₃O₄) layer will lead to someloss of transparency and luster. The reduction is performed so that theiron of the iron oxide typically comprises from about 1% to about 30%Fe(II) and from about 70% to about 99% Fe(III). The reduction may beperformed so that the iron of the iron oxide comprises from about 12% toabout 18% Fe(II) and from about 82% to about 88% Fe(III). The reductionmay be performed so that the iron of the iron oxide comprises from about14% to about 16% Fe(II) and from about 84% to about 86% Fe(III). In oneembodiment, the amount of iron, in the iron oxide, is about 1% to about15% of the weight of the pearlescent pigment.

Other metal oxides maybe reduced by this procedure. The reduction may beperformed so that about 1% to about 30% of the metal in the metal oxidehas been reduced. The reduction may be performed so that about 12% toabout 18% of the metal in the metal oxide has been reduced. Thereduction may be performed so that about 14% to about 16% of the metalin the metal oxide has been reduced. In one embodiment, the amount ofmetal, in the metal oxide, is about 1% to about 15% of the weight of thepearlescent pigment.

Homogeneous hydrogenation of suspensions containing metal oxide coatedmica-based pigments allows much greater control of the oxidation stateof the deposited iron oxide layers, compared to conventional hightemperature calcination in a reducing (H₂/N₂) atmosphere. Thus, thisprocessing technique may allow more precise control over pigment colorand luster. In addition, the two step process of metal oxide depositionfollowed by liquid phase hydrogenation may yield pearlescent pigmentswith a smooth texture and improved rub-resistance relative to existingmethodologies (e.g. mixtures, etc.). An example of the metal oxide thatmay be reduced is FeOOH.

One method of reduction uses a liquid-phase hydrogenation set-upconsisting of three main components: 1) the hydrogen reservoir (equippedwith N₂ purging); 2) a pressurized reaction chamber (with a 45° pitchagitation blade and an electrical heating mantle); and 3) a blow-outcollector reservoir in case of over-pressure situation. The system isfully enclosed to minimize the risk of gas explosion. The pigments arefirst dispersed in a non-oxidizing (or mildly reductive) liquid, whichhas a reasonable H₂ gas solubility. Generally speaking, the higher thegas pressure, the higher the H₂ concentration in the carrying medium,and therefore the faster the reduction reaction. Higher temperatures andthe addition of a noble metal catalyst also speed up the reaction. Thedegree of reduction, or the lightness (or darkness) of the final pigmentare most effectively controlled by the length of reduction time andcatalyst loading.

Some examples of solvents are PEG 400 (polyethylene glycol of molecularweight 425 g/mol) and NMP (N-methylpyrrolidone). Other solvents orliquids such as ethylene glycol, PEG 200, dimethylformamide and watercan also be used. PEG 400 is most favored due to its high chemicalstability (i.e., reusable for many runs), high boiling point (i.e.,enabling high temperature reduction), low vapor pressure, lowflammability, high H₂ solubility, good wetting power to the pigment(i.e., excellent dispersion and maximum surface exposure to H₂), goodwetting power to the catalyst (i.e., maximize catalytic surface), andmoderate viscosity (45 cP) for the ease of processing, which should behigh enough to keep mica pigments from settling even under gentleagitation, and low enough to be filtered out under mild vacuumfiltration condition. NMP may also be used. The hydrogenation pressuremay be from atmospheric pressure, or above atmospheric pressure to about70 bar. The pressure may be from about 10 bar to about 40 bar, or fromabout 10 to about 25 bar. The temperature may be from room temperatureto about 220° C., or from 200-220° C., below the degradation temperatureof the solvents. The agitation is usually kept below about 300 RPM toavoid fragmenting the pigment. The mica based pigments are usually veryfragile and can break under high shear. Fragmentation usually leads tothe rise of opacity and loss of luster. The concentration of thecatalyst may be about 0.001 to about 0.2 g of catalyst per kilogram ofliquid medium. In one embodiment the concentration of the catalyst maybe about 0.01 to about 0.08 g of catalyst per kilogram of liquid medium.

Examples of noble metal catalysts include, but are not limited to Pd,Pt, PtO₂ (Adam's catalyst), Rh, Au, Ag, and Ta. The catalyst may beoxides, hydroxides or other derivatives of noble metals. The catalystcan come in supported or unsupported forms. Examples of supported formsinclude, but are not limited to Pd and Pt metals deposited onto charcoalor carbon based supports (coconut shell, etc.), alumina, zeolite orother inorganic substrates (support). The size of support can range fromseveral millimeters to as small as 10-20 microns. Due to the highersurface to volume ratio, catalysts on smaller support can have a highermetal loading and thus higher catalytic activity. However, due to thesize and density similarity to interference pigments, (i.e., 25-75micron, SG of 3-5), catalysts of small support can be difficult toseparate from the pigment, recover and reuse. The use of supportedcatalysts the size of about 1 mm and above, can be easily separated frompearlescent pigments by dry sieving using sieves of 80-120 mesh size.The large-support catalysts, including but not limited to Escat® 3 mm(Pt on alumina) are easily separated; they have relative low efficiency,and thus are useful for shallower hydrogenation that produces lightercolor antique pearls such as antique copper and antique bronze.

Nanoparticulate metal catalysts are useful for deep hydrogenation toobtain extremely dark color. In one embodiment, commercially obtainedbulk PtO₂ powder (usually 10-50 micron diameter) is wet milled withPEG400 in an intensive media mill using 0.5 mm zirconia media for 8 to16 hours. The final particle size is submicron (ie., colloidal size),and the PtO₂ can suspend in PEG 400 liquid for a couple days withoutsettling. Since the majority of the interference pigment will settle inPEG 400 within an hour or so, sedimentation may be used as a separationprocess to recover colloidal PtO₂ from the pigment slurry. The majorityof colloidal PtO₂ will remain in supernatant phase to be decanted andreused. Such method provides for an efficient liquid-phase hydrogenationof metal oxide coated mica pigments.

In one embodiment the catalyst nanoparticulate has a mean diameter fromabout 53 to about 55 nm. The median particle size may be about 40 nm.

A colloidal fluid of stabilized metal nanoparticles, such as Ptnanoparticles (Pt-NP) may be used as the catalyst for hydrogenation.Pt-NP catalytic fluid is prepared by a polymer stabilizeddirect-reduction method. The Pt nanoparticles are of 2-5 nm in size, andare stabilized by polyvinylpyrrolidone (PVP) polymer. This embodimentoffers several benefits over micronized PtO₂ catalyst and industriallyavailable hydrogenation catalysts mentioned above. First, it is thoughtthat the extremely large surface area of Pt colloid allows for the useof less catalyst, and much more intimate contact between the catalystand the substrate. Secondly, a small particle size and the presence of alubricating polymer (PVP), help reduce the friction between thesubstrate and catalyst, which may lead to better preservation of surfacesmoothness and luster of the pigment. Third, this catalytic fluid isthermodynamically stable. The long shelf-life is a big advantage overthe micronized PtO₂ catalyst, which requires periodically re-milling tosustain catalytic efficiency.

After hydrogenation, the pigment is subjected to an optional washingstep to remove the Pt residue. PVP, a known chelating agent to Pt and areducing agent to platinum salt, is useful as a 10% PVP aqueous washingsolution to remove the free Pt-NP in the supernatant, Pt-NP absorbedonto substrate and any trace of Pt ions that might be present.

The deposition of FeOOH followed by hydrogenation may be utilized toprogress the interference color associated with pearlescent, TiO₂coated, mica-based pigments. Transparent, pearlescent TiO₂ coatedpigments may be transformed into lustrous colored pearlescent pigmentsusing the described methodology. For relatively thin FeOOH deposition,hydrogenation results in pigments characterized by the same interferencecolor with increased opacity. The interference color may be progressedto the next shade (for instance, from violet to blue or blue to green)through reduction of relatively thick FeOOH coatings. This process alsosignificantly increases the opacity of the resulting pearlescentpigment. Thus, various vibrant, multi-colored pigments may be producedin all four quadrants of the CIELAB color space with controlled opacityallowing for significantly improved formulation flexibility.

In one embodiment of a black/antique pearlescent pigment, the synthesisstarts with choosing an appropriate substrate. The choice of substrateaffects the undertone and transparency of color of the black/antiquepearl interference pigment. For example, to yield an antique burgundylook, it is important to choose a substrate with deep red or deep marooncolor, such as hematite (i.e., high temperature calcined Fe₂O₃) coatedmica. This undertone in combination with an iron oxide (FeO, FeO—Fe₂O₃,Fe₃O₄) top layer will produce various shades of burgundy colors. Fe₂O₃or TiO₂ coated synthetic or natural mica has colors ranging from red toyellow and blue to green. The color of substrate dictates the undertoneof final pearl appearance. It is also desirable to choose a substratewith high transparency so that it can faithfully emulate the “airy” lookof high quality natural pearl. Generally speaking synthetic mica (suchthose made by CQV), glass flakes layer (for instance from Nippon Sheetglass), borosilicate and synthetic alumina substrates are preferred overnatural mica for higher transparency. Such substrates may be multilayermaterials i.e. include materials of different refractive indices.

In one embodiment the pearlescent pigment is an inorganic material, andthe color of a homogeneous coating of the pigment, measured over a whitebackground, is selected from the group consisting of: a CIELAB hueangle, h_(ab), from about 50 to about 80 degrees, wherein L* is not morethan about 85, and the chroma value is greater than 22; a CIELAB hueangle, h_(ab), from about 80 to about 275 degrees, wherein L* is notmore than about 80, and the chroma value is greater than about 10; and aCIELAB hue angle, h_(ab), from not less than about 275 to not more thanabout 50 degrees, wherein L* is not more than about 85, and the chromavalue is greater than about 9.

In one embodiment the pearlescent pigment is an inorganic material, andthe color of a homogeneous coating of the pigment, measured over a whitebackground has a CIELAB hue angle, h_(ab), from about 50 to about 80degrees, wherein L* is not more than about 85, and the chroma value isgreater than 22. The L* may be not more than about 80, about 75, orabout 70. The chroma value may be greater than about 24, about 26, orabout 28. In one embodiment the CIELAB hue angle, h_(ab), is from about50 to about 65 degrees.

In one embodiment the pearlescent pigment is an inorganic material, andthe color of a homogeneous coating of the pigment, measured over a whitebackground has a CIELAB hue angle, h_(ab), from about 80 to about 275degrees, wherein L* is not more than an about 80, and the chroma valueis greater than about 10. The L* may be not more than about 75, about70, or about 65. The chroma value may be greater than about 12, about14, or about 16.

In one embodiment the pearlescent pigment is an inorganic material, andthe color of a homogeneous coating of the pigment, measured over a whitebackground has a CIELAB hue angle, h_(ab), from not less than about 275to not more than about 50 degrees, wherein L* is not more than about 85,and the chroma value is greater than about 9. The L* may be not morethan about 80, about 75, or about 70. The chroma value may be greaterthan about 11, about 13, or about 15.

In one embodiment the pearlescent pigment is blue, with a CIELAB hueangle, h_(ab), from about 170 to about 275 degrees, measured over awhite background using a D65 illuminant and a 10 degree observer. Bluepearlescent pigments may be produced that do not contain iron blue(ferric ferrocyanide), allowing the pigment to be used in cosmeticapplications involving the lip area, such as lip gloss, lipstick, andother lip formulations. In addition, the blue pearlescent pigments aremore stable than ferric ferrocyanide, which decomposes in alkaline pHresulting in pigment bleeding and marked changes in pigment color.Another advantage of the blue pearlescent pigments is that they do notrestrict the pigment to the color space defined by ferric ferrocyanide.Iron Blue is a powerful colorant that only allows the pigment designerto formulate pigments within a well defined, narrow color space andrestricts formulation flexibility, see Dyes and Pigments 56 (2003)93-98.

In one embodiment the pearlescent pigment is green, with a CIELAB hueangle, h_(ab), from about 80 to about 170 degrees, measured over a whitebackground using a D65 illuminant and a 10 degree observer. Greenpearlescent pigments may be produced that do not contain chromium oxide,allowing the pigment to be used in cosmetic applications involving thelip area, such as lip gloss, lipstick, and other lip formulations. Mostcommercially available green pearlescent pigments are based on chromiumoxide deposition, U.S. Pat. No. 6,485,556.

In one embodiment the pearlescent pigment is red, pink, or violet, witha CIELAB hue angle, h_(ab), from not less than about 275 to not morethan about 50 degrees, measured over a white background using a D65illuminant and a 10 degree observer. Red, pink, or violet mica-basedpearlescent pigments may be produced that do not contain carmine.Carmine is a colorant used extensively in the cosmetic industry eitherdirectly or combined with pearlescent pigments (such as in Cloisonné®Red by Engelhard/BASF). It is extremely sensitive to UV exposure and mayfade over time. Carmine is also unstable in acidic environments. It isoften characterized by colorant bleeding in cosmetic formulations, suchas nail polish. In addition, carmine (which is extracted from insects)has been linked to numerous reports of allergic reactions, includinganaphylaxis. The development of carmine-free red, pink and violet shadesis particularly advantageous because it offers formulators a more stableand hygienic alternative. In one embodiment the pearlescent pigment doesnot contain carmine.

In another embodiment, the pearlescent pigment has a HPI of less thanabout 1 when measured in a 76 μm thick film formed from 10 wt % of thepigment in acrylic enamel. The HPI may be less than about 0.5. The HPImay range from about 0.05 to about 0.5.

There are relatively few dark colored (or antique-looking) pearlescentpigments currently offered in the market, examples of such are: Timica®and Cloisonné Nu-Antique® lines by Engelhard/BASF. The existing darkpearlescent products in the market are too opaque and too dull (i.e.,not enough luster), and not dark enough to emulate the natural blackpearl effect (e.g., Tahiti black pearl). In addition, they exhibit anundesirable darkening effect when applied and rubbed on the skin. Onemethod to solve these problems is to use a dark colored layer on top orbeneath the interference layer as a smooth film, to minimize lightscattering, and thus preserve the luster and transparency of thepigment.

In one embodiment the pearlescent pigment is an inorganic material andthe color of a homogeneous coating of the pigment, measured over a whitebackground, has a CIELAB L* value of about 30 or less and a chroma valueof about 3 or less. The L* may be not more than about 28, about 25, orabout 22. The chroma value may be less than about 2.5, about 2, or about1.5. These methods have been used to produce very dark antique/blackpearl interference pigments. The darkest color achieved based on a 5%pigment drawdown in a nitrocellulose varnish is in the range of about 29to about 32 in terms of lightness value (L* value in CIE1976 colorspace, measured using a 10 degree observer, illuminant D65 with SpecularComponent Included), which is very close to the reference LENETA cardblack (L*=28) along with a very low chroma (typically less than 3).Titan® ST is the range of L*=64 to 65, Engelhard's Cloisonné NU-AntiqueSeries is in the range of L*=37 to 60. In all cases, these are muchlighter and less lustrous than the pigment formed by this process.

The methods described may produce pigments with better hiding powerwhile maintaining a high luster. The pigments may have better stabilitythan current pigments at high and low pH, and are less likely to bleed.

In one embodiment the pearlescent pigment is an inorganic material andthe ΔE* of the alkaline stability for a homogeneous coating of thepigment, measured over a white background, is less than about 2.

In one embodiment the pearlescent pigment is an inorganic material andthe ΔE* of the acid stability for a homogeneous coating of the pigment,measured over a white background, is less than about 4.

In one embodiment the pearlescent pigment is an inorganic material andthe ΔE* of magnetically aligned and non-aligned homogeneous coatings ofthe pigment, measured over a white background, is not less than 20.

In one embodiment the pearlescent pigment has a magnetic susceptibilityof about 0.1×10⁻⁵ to 7.5×10⁻⁵ m³/kg.

The pigments may be magnetic or exhibit magnetic susceptibility. Influid-based systems, such as liquid coatings or uncured plasticpreparations containing these pigments, an applied magnetic field may beused to align pigments in specific regions of the coating to createimages that appear to be three-dimensional. After the pigments have beenaligned, the coating may be cured to solidify the image.

The three-dimensional effect is produced by the pigment particlesaligned at non-parallel or intermediate angles with respect to thecoating surface. In an applied electric field, the high aspect ratioplatelets will align themselves such that the longest dimension of theplatelet (namely, the platelet width) aligns itself along the magneticfield lines. The ability to reorient the colored particles allows themto be manipulated to specific angles resulting in a controlledthree-dimensional appearance. In regions of where the field lines areperpendicular to the observer, the platelet particles will beperpendicular to the observer resulting in a jet black appearance. Thisextremely dark appearance is due to light scattering at the particleedges and the absence of a reflective surface. In regions devoid of anapplied magnetic force, the particles align more substantially parallelto the applied coating surface resulting in the intensely coloredappearance. Applying a magnetic field parallel to the coating surfacewill orient more of the pigments parallel to the surface resulting in aeven more intensely colored appearance.

In one embodiment a cosmetic composition contains the pearlescentpigment. The cosmetic composition may be useful for make-up products forthe skin, the eyes, or hair. Examples of compositions intended asmake-up for the skin include eye shadows, eye liners, mascaras, body orface powder, foundations, blushes, colored creams, nail polish,lipsticks, lip gloss, hair or body gel, hair or body wash, cover sticks,lotion, concealer and foundation. Examples of cosmetic applicationsinvolving the lip area, are lip gloss, lipstick, and other lipcompositions. Nail polish may be referred to as nail varnish, or nailenamel.

Pearlescent pigments may be used to produce a makeup cosmetic asdescribed in U.S. Pat. No. 6,663,852, U.S. Pat. No. 6,451,294, and U.S.Pat. No. 6,280,714.

In one embodiment, the pigments of the composition are aligned during orafter application of the composition. An example of aligning thepigments of the composition is by applied the composition with amagnetic applicator. The magnetic applicator may be used to align themagnetic particles in the cosmetic allowing control of their appearance.

General cosmetic compositions may contain preservatives, stabilizers,neutralizing agents, aqueous-phase thickeners (polysaccharidebiopolymers, synthetic polymers) or fatty-phase thickeners, such as clayminerals, fillers, perfumes, hydrophilic or lipophilic activesubstances, surfactants, antioxidants, film-forming polymers andmixtures thereof. The amounts of these various ingredients are thoseconventionally employed in the fields in question and, for example, maybe from 0.01 to 30% of the total weight of the composition. In oneembodiment, the cosmetic composition may further comprise a binderwherein the pigment represents about 0.5% to about 99.5% of thecomposition.

Lip cosmetic composition may comprise any ingredient usually used in thefield concerned, such as water, preferably in an amount ranging from 0to 95% of the total weight of the composition, water-soluble orliposoluble dyes, antioxidants, essential oils, preserving agents,fragrances, neutralizing agents, liposoluble polymers, in particularhydrocarbon-based polymers such as polyalkylenes or polyvinyl laurate,gelling agents for an aqueous phase, gelling agents for a liquid fattyphase, waxes, gums, surfactants, additional cosmetic or dermatologicalactive agents such as, for example, emollients, moisturizers (forexample glycerol), vitamins, liquid lanolin, essential fatty acids,lipophilic or hydrophilic sunscreens, and mixtures thereof. Thecomposition may also contain lipid vesicles of ionic and/or nonionictype. These ingredients (other than the water) may be present in thecomposition in a proportion of from 0 to 20% of the total weight of thecomposition.

In one embodiment a coating or ink composition contains the pearlescentpigment. In another embodiment an article comprises the pearlescentpigment. A coating, ink, or article may further comprise a binder,wherein the pigment represents about 0.5% to about 99.5% of thecomposition, about 0.1% to about 70%, or about 0.2% to about 10%.

The coating or ink may be printing ink, surface coating, coatings forlaser marking, pigment preparation, dry preparation, food colorant,textile coating, architectural coating, synthetic fiber, or fiber basedproduct. A coating may be applied to an object as a liquid, vapor, orsolid. Examples of methods for applying a coating are by printing,painting, polymeric coating, or spraying. The coating may be a powder,enamel, aerosol, paint, epoxy, or polymer.

The ink may be a magnetic toner. An example of a magnetic toner is onethat is used for Magnetic Ink Character Recognition (MICR). These tonersmay be used to print security codes on checks and are read by low-costreaders. Many of the toners used for MICR are black. The color andmagnetic susceptibility of the MICR ink may be adjusted by usingdifferent pearlescent pigments.

The arts of making coatings and inks, as well the various printingprocesses (i.e., intaglio, flexo, screen, offset, gravure) are very wellknown in the literatures, so it is not repeated here [see “The PrintingInk Manual”, 5^(th) edition, R. H. Leach, ed. Taylor & Francis, Inc.].Other less common printing processes include digital offset solutionssuch as the Hewlett-Packard Indigo presses.

Besides the topical applications such as printings or coatings, thepigments can be incorporated directly into substrates during theformation stage to make an article. For example, to a papers, thepigments can be introduced along with other regular paper fillers suchas calcite, talc during paper making to fill the open pores of papernear the surface. If the article is a plastic, the pigment can beintroduced during the extrusion of substrate. Examples of articles areplastic, glass, ceramic material, concrete, pressed wood, pills, paper,toothpaste, food products, or agricultural products.

The terms goniochromatic, iridescent, and pearlescent, may be usedinterchangeably to mean a change of color depending on the viewingangle.

Unless otherwise specified, the alkaline stability of a pigment ismeasured as ΔE* measured against a white background, using the proceduredescribed in Example 32.

Unless otherwise specified, the acid stability of a pigment is measuredas ΔE* measured against a white background, using the proceduredescribed in Example 33.

Unless otherwise specified, the HPI, CIELAB coordinates, hue angle,h_(ab), L*, a*, b*, and chroma of a pigment are measured using thepigment drawdown described in Example 32 with a white or blackbackground using a D65 illuminant and a 10 degree observer.

A homogeneous coating of a pigment is a coating that only contains onecolored element, it is not a blend of colored elements. An example of apigment that will not form a homogeneous coating is Cloisonné® NuAntique Gold pigment, the pigment contains both color pigment and ironoxide.

EXAMPLES Example 1 FeCl₃—Urea Homogenous Hydrolysis Process forDepositing an Easily Reducible FeOOH Layer

-   -   A 0.1M HCl solution (356.9 g) was added to a 500 ml cylindrical        reaction vessel blade (for gentle stirring and non-sticking        property). The solution was stirred at 175 RPM. A 7.1 g 45% wt        FeCl₃ Stock Solution (Riedel 12322, 45% wt FeCl₃, 55% water) was        add drop-wise into the reactor.    -   Urea (16 g) was added slowly into reactor under agitation.    -   Sky Chemical Russet Pigment (20 g) was added to the reactor, and        stirred for 5 minutes.    -   The temperature was increased 2° C./min to 80° C. and held for 4        hour.    -   The pigment is recovered by filtration and washed with distilled        water.

Example 2 Solid-on-Solid Catalytic Aqueous-Phase Hydrogenation Process

Step 1—Wet Micronization of Catalyst

-   -   Platinum oxide powder (200 mg, 10-50 micron grade,        Aldrich 206032) was stirred in 100 g PEG 400 (i.e., 2 mg PtO2/g        fluid).    -   The slurry was loaded into a Eiger-Mill equipment with 0.5 mm        zirconia media and water cooling jacket. The power was set to        maximum and ran for 6 hours. The final slurry was a greenish        black and did not settle for about 1 to 2 days.    -   The particle size was checked with dynamic light scattering        (Horiba DLLS Particle Sizer) and OM (optical microscope, Nikon)        to ensure no particles larger than 1 micron were left.

Step 2—Hydrogenation

-   -   PEG 400 (100 g), FeOOH (20 g) coated red pearl pigment (i.e.,        Sky Chemical Super Russet) and 3 g of the micronized PtO₂ slurry        (2 mg catalyst/g fluid) from step 1, was loaded into a        steel-constructed hydrogenation chamber.    -   An agitator was lowered into the chamber. The chamber was closed        and connected to the H₂ reservoir.    -   The gas line was purged several times with N₂.    -   The chamber was pressurized with H₂ to roughly 10-14 bar.    -   The agitator was turned on and the heating mantle was set to        200° C. The reaction was run for 6 hours.    -   The heating mantle was removed to let the chamber cool. The        chamber head space and lines were purged with N₂ gas to remove        any residual H₂.    -   The chamber was opened and the slurry was poured out into a        container.

Step 3—Catalyst Recovery and Pigment Wash

-   -   The slurry was settled in the container. The pearl pigment will        sink to the bottom much faster than colloidal PtO₂. As soon as        the majority of the pigment settled, the supernatant was        decanted, which was rich in PtO₂, and put aside for reuse.    -   The settled pigments were then washed several times with water        and one time with industrial alcohol on a mesh filter (20 micron        mesh) to remove the PEG and residual colloidal PtO₂.    -   The pigment was dried under mild vacuum.

Example 3 Preparation of Homogenous Platinum Colloidal NanoparticleCatalyst

-   -   Polyvinylpyrrolidone (PVP) Reductant Solution: Anhydrous        ethylene glycol (80 g) and K15 PVP (10 g, Fluka 81390 or ISP)        were mixed at 3000 RPM with a Hauschild mixer until dissolved.        The mixture was added to a 1 L 3.5″ Teflon Coated Cylindrical        reactor with a 2″ PTFE coated 3-leaf blade, and a nitrogen        purging line.    -   Precursor Solution: Anhydrous ethylene glycol (80 g) and        H₂PtCl₆-6H₂O salt (0.5 g, SA C3044) were added to a 4 oz jar        with a magnetic stir bar, and stirred until dissolved. The        liquid was sonicated for 10 minutes to remove oxygen then added        to the PVP reductant solution.    -   Mixing of Precursor and Reductant: Anhydrous ethylene glycol        (80 g) was added to the reaction vessel, followed by agitation        at roughly 200 RPM to gently mix precursor with reductant at        room temperature. The N₂ purging line was lowered to just below        the liquid surface to provide an insert gas blanket.    -   Thermal Activation: The mixture was heated from approximately        20° C. to 120° C. in roughly 100 minutes. The mixture was held        at 120° C. for 1 hour before switching off the heat. The        solution was allowed to cool in the oil bath back to room        temperature.    -   Recovery: The Pt-in-(PVP+EG) liquid [0.75 mg Pt/q-fluid] was        poured into a glass jar and the jar was sealed.

Example 4 Liquid-Phase Hydrogenation Process with a Homogenous Catalyst

Step 1—Hydrogenation

-   -   PEG 400 (100 g), FeOOH coated red pearl pigment (20 g, i.e., Sky        Chemical Super Russet), and Pt colloidal solution (8 g) from        Example 3 (300 ppm level of Pt, normalized to dry content of        pigment) was loaded into a steel-constructed hydrogenation        chamber.    -   An agitator was lowered into the chamber. The chamber was closed        and connected to the H₂ reservoir.    -   The gas line was purged several times with N₂.    -   The chamber was pressurized with H₂ to roughly 10-14 bar.    -   The agitator was turned on and the heating mantle was set to        200° C. The reaction was run for 6 hours.    -   The heating mantle was removed to let the chamber cool. The        chamber head space and lines were purged with N₂ gas to remove        any residual H₂.    -   The chamber was opened and the slurry was pour out into a        container.

Step 2—Catalyst Recovery and Pigment Wash

-   -   After the slurry was allowed to settle in a container, the        supernatant fluid was discarded.    -   The settle pigments were then washed several times with 10% PVP        in water and one time with industrial alcohol on a mesh filter        (20 micron mesh) to remove PEG and residual colloidal Pt.    -   The pigment was dried under mild vacuum

Example 5 Onyx Black Pearlescent Pigment

Step 1—FeOOH Deposition by FeCl₃-Urea Homogenous Hydrolysis

-   -   A 0.1M HCl solution (10,707 g) was added to a 15 L cylindrical        reaction vessel. The solution was stirred at 175 RPM. A 213 g        FeCl₃ Stock Solution (Riedel 12322, 45% wt FeCl₃, 55% water) was        added drop-wise into the reactor.    -   Urea (1440 g) was added slowly into reactor under agitation.    -   Sudarshan Russet Pigment (600 g) was added to the reactor, and        stirred for 5 minutes. This deposition technique is not        exclusive to the Sudarshan Russet pigment. Other platelet-like        substrates may be used including those comprising synthetic mica        (uncoated or metal oxide coated) or flaky glass supports. These        substrates may contain multiple adsorbed layers, such as those        that contain materials of varying refractive index. It is        important to note that equivalent levels of Fe uptake (g Fe/g        mica) can be achieved using both pre-coated or uncoated supports        by either redeposition or by adjustment of the reaction        conditions.    -   The reaction temperature was increased 2° C./min to 90° C. and        held for 4 hour.    -   The coated pigment was then recovered by vacuum filtration using        a 10 micron filter. The filter cake was washed three times with        5 L of water.    -   The coated pigment was then dried at 60° C. overnight.

Step 2—Hydrogenation

-   -   PEG 400 (1920 g), FeOOH coated red pearl pigment (400 g, i.e.,        Sudarshan Russet), and Pt colloidal solution (80 g) from Example        3 was loaded into a steel-constructed hydrogenation chamber.    -   An agitator was lowered into the chamber. The chamber was closed        and connected to the H₂ reservoir.    -   The gas line was purged several times with N₂.    -   The chamber was pressurized with H₂ to roughly 340-380 psig.    -   The agitator was turned on and the heating mantle was set to        200° C. The reaction was run for 6 hours.    -   The heating mantle was then removed to let the chamber cool. The        chamber head space and lines were purged with N₂ gas to remove        any residual H₂.    -   The chamber was opened and the slurry was poured out into a        container.    -   The hydrogenated pigment was then recovered by vacuum filtration        using a 10 micron filter. The filter cake was washed with 4 L of        water followed by 2 L of ethanol.    -   The pigment was then placed in an oven at 60° C. for 24 hours.

Step 3—Pigment Drawdown Preparation

-   -   The hydrogenated pigment (0.5 g) was dispersed in 4.5 g of PPG        Delstar PMR499 acrylic enamel in a max 15 translucent jar        designed for the DAC150FVZ-K model (Hauschild Engineering) high        speed mixer.    -   Glass beads (2 g) were added to the dispersed suspension.    -   The pigment suspension (10% pigment) was then mixed for 3        minutes at 3000 rpm using a DAC150FVZ-K model high speed mixer.    -   Three preparations of the same 10% pigment suspension were        prepared using the procedure described above. Directly following        mixing, each pigment suspension was applied to a Form 2C Leneta        card using either a 1.5, 3 or 6 mil Bird applicator.    -   Each drawdown was allowed to dry at room temperature for 30        minutes and then placed in an oven at 60° C. for an additional        30 minutes.    -   The colorimetric parameters (CIE L*a*b*) of the dried films were        measured using a 10 degree observer and D65 illuminant (specular        component included and specular component excluded) against both        a white and black reference background. The results of these        measurements are listed in the tables below.

TABLE 1 Colorimetric parameters (CIE L*a*b*) of Onyx black (Example 5)drawdowns (10% pigment) using a 10 degree observer and D65 illuminantwith specular component included (SCI) at varying film thickness with ablack background reference. Sample Over Black Background Uncoated BlackBackground Thickness L* a* b* C* H L* a* b* C* h 1.5 mil 29.34 1.01−1.82 2.08 299.03 27.32 0.32 −0.01 0.32 357.88 3.0 mil 29.75 1.58 −2.162.68 306.14 27.40 0.35 −0.07 0.35 349.26 6.0 mil 28.89 1.29 −2.03 2.41302.5 27.19 0.27 −0.19 0.33 325.25

TABLE 2 Colorimetric parameters (CIE L*a*b*) of Onyx black (Example 5)drawdowns (10% pigment) using a 10 degree observer and D65 illuminantwith specular component included (SCI) at varying film thickness with awhite background reference. Sample Over White Background Uncoated WhiteBackground Thickness L* a* b* C* H L* a* b* C* h 1.5 mil 43.14 1.21−0.70 1.40 329.97 93.36 −0.80 3.23 3.33 103.89 3.0 mil 30.87 1.57 −1.892.46 309.78 93.41 −0.77 3.18 3.27 103.64 6.0 mil 28.88 1.27 −2.03 2.39301.93 93.44 −0.63 3.33 3.39 100.76

TABLE 3 Colorimetric parameters (CIE L*a*b*) of Onyx black (Example 5)drawdowns (10% pigment) using a 10 degree observer and D65 illuminantwith specular component excluded (SCE) at varying film thickness with ablack background reference. Sample Over Black Background Uncoated BlackBackground Thickness L* a* b* C* H L* a* b* C* h 1.5 mil 11.17 1.71−2.48 3.01 304.59 8.15 1.03 1.85 2.12 60.92 3.0 mil 13.89 2.82 −2.944.07 313.8 7.90 1.17 2.15 2.45 61.59 6.0 mil 14.88 2.27 −2.62 3.46310.90 8.12 0.93 1.72 1.95 61.62

TABLE 4 Colorimetric parameters (CIE L*a*b*) of Onyx black (Example 5)drawdowns (10% pigment) using a 10 degree observer and D65 illuminantwith specular component excluded (SCE) at varying film thickness with awhite background reference. Sample Over White Background Uncoated WhiteBackground Thickness L* a* b* C* H L* a* b* C* h 1.5 mil 36.28 1.02 0.091.02 4.79 91.74 −0.80 3.30 3.39 103.65 3.0 mil 16.84 2.61 −2.28 3.47318.85 91.58 −0.77 3.33 3.42 103.07 6.0 mil 15.14 2.36 −2.70 3.59 311.0591.69 −0.75 3.26 3.34 103.03

Example 6 Neon Green-Gold Pearlescent Pigment

A mixture of HCl (706.2 g of 0.1 M solution), FeCl₃ (14.2 g of 45 wt %solution), urea (96 g), and TiO₂ coated natural mica pigment (40 g,SunPearl Iridescent Green, 10-60 μm particle size) was charged into a 1L jacketed pot reactor under agitation at 180 rpm. The mixture had a pHof approximately 1.8. The mixture was then heated to 90° C. The pigmentis complete when urea decomposition resulted in a rise of the solutionpH to between about 6.3 and 6.5. After about 2 hours at 90° C., thepigment was filtered, rinsed with deionized water, and dried at 60-80°C. A neon-like lustrous pigment having a green interference colorcombined with a golden yellow absorbance color was obtained. Theresulting pigment contained approximately 6.5 wt % elemental iron asmeasured using a Perkin Elmer 5100 PC Atomic AbsorptionSpectrophotometer. CIELAB values measured for this pigment and thestarting substrate with a Spectraflash SF600 Plus spectrophotometer arelisted in Table 5.

Example 7 Neon Gold Pearlescent Pigment

A neon gold pearlescent pigments was prepared via the same techniquedemonstrated in Example 1, except the amount of each reagent initiallycharged to the reaction vessel is different as depicted in Table 6. Asshown in Table 6, the amount of FeCl₃ used for coating was twice thatused in Example 1 with the same Urea/Fe molar ratio of 40.6 and the samestarting substrate. Following filtration, washing, and drying, aneon-like lustrous pigment having a golden interference color wasobtained (see Table 5 for CIELAB values). The resulting pigmentcontained approximately 10.7 wt % elemental iron.

This example illustrates thicker coatings of FeOOH layers on TiO₂-coatedplatelet-like substrates can be utilized to progress the interferencecolor to the next shade. This is evident by comparison of the hue anglemeasured over a black background (see Table 5) for the coated substratesand the starting material. The uncoated substrate has a greeninterference color with a hue angle of 205.1. FeOOH coating progressesthe hue angle clockwise with increasing thickness. As shown for areaction Fe/pigment mass ratio of 0.055 (or 6.5 wt % Fe in the finalpigment), the hue angle progresses from a green interference color (hueangle=205.1) to a green-gold interference color (hue angle=108.6). Atabout double the reaction Fe/pigment mass ratio (which results in 10.7wt % Fe in the final pigment), the hue angle further progresses to amore golden interference color (hue angle=83.0).

Increased FeOOH deposition results in a darkening of the substrate, or adrop in the L* value, as shown in Table 5. The L* value of the startingmaterial with both white and black backgrounds is reduced as theFe/pigment mass ratio used in deposition is increased.

TABLE 5 CIE Lab values measured for Examples 6 and 7 using a 10°observer and D65 illuminant with specular component included. Pigmentdrawdowns (3 mil Bird applicator) were prepared by dispersing 0.75 gpigment in 5 g of vehicle (10% CAB 531-1 (Eastman Chemical) in n-butylacetate). Reaction Final White Background Black Background Fe/PigmentInterference L* a* b* Hue L* a* b* Hue Example Ratio (g/g) Color valuevalue value Chroma Angle value value value Chroma Angle SunPearl 0Transparent 92.8 −2.3 5.6 6.0 112.5 79.9 −12.7 −6.0 14.0 205.1Iridescent Green Green 6 0.055 Transparent 78.2 3.7 35.5 35.5 84.1 72.8−9.2 27.5 29.0 108.6 Green/Gold 7 0.110 Transparent 74.7 12.4 46.9 48.575.2 68.4 4.7 38.3 38.6 83.0 Gold

TABLE 6 Quantity of reagents used for Fe(OH)₃ deposition oncommercially- available TiO₂-coated natural mica substrates. InitialReaction Solution Composition 45 wt % Exam- Pigment FeCl₃ Urea 0.1 M pleSubstrate Brand Name (g) (g) (g) HCl (g) 6 SunPearl Iridescent Green 4014.2 96 706.2 7 SunPearl Iridescent Green 40 28.4 192 706.2 10 SunPearlIridescent Gold 40 14.2 96 706.2 11 SunPearl Iridescent Gold 40 28.4 192706.2 14 SunPearl Iridescent Red 40 3.55 24 706.2 15 SunPearl IridescentRed 40 7.1 48 706.2 16 SunPearl Iridescent Red 40 14.2 96 706.2 20SunPearl Iridescent Violet 40 14.2 48 706.2 21 SunPearl IridescentViolet 40 28.4 192 706.2 24 SunPearl Iridescent Blue 40 14.2 48 706.2 25SunPearl Iridescent Blue 40 28.4 192 706.2

Example 8 Lustrous, Semi-Opaque Green Pearlescent Pigment

The pigment prepared in Example 6 (20 g, Mica+TiO₂+Fe(OH)₃, particlesize of 10-60 μm) and PVP stabilized Pt catalyst (4 g) in ethyleneglycol (prepared in Example 3) were dispersed in polyethylene glycol 400(96 g, PEG 400, EMD Chemical, CAS 25322-68-3), and added to a 600 mLsteel Parr reactor equipped with twin 45 degree pitch blade impellers.The mixture was agitated at approximately 800 rpm. The reaction solutionwas purged several times by pressurizing the vessel with nitrogen andthen evacuating under vacuum. Following sufficient purging, the mixturewas heated to 220° C., pressurized with hydrogen to 10.3 bar and held atthese conditions for 6 hours. The pigment was filtered, rinsed with 4 Ldeionized water followed by 1 L ethanol, and dried at 60-80° C. A deepand intensely colored, semi-opaque, green pearlescent pigment (see Table7 for corresponding CIE Lab color values) was obtained.

The weight fraction of Fe(II) and Fe(III) in the final pigment is givenin Table 8. Total iron and Fe(II) content was determined via atomicabsorption spectroscopy and oxidation/reduction titration with 0.1 Npotassium dichromate, respectively. The hydrogenation resulted inreduction of approximately 15.4% of the deposited iron (Fe(III) toFe(II)).

As shown in Table 7, this reduction process transformed the bichroicstarting material (Example 6) into a more opaque pigment with moreuniform color coordinates as measured with white and black backgrounds.The level of opacity, or hiding power can be described using a hidingpower index (HPI) defined as:

$\begin{matrix}{{H\; P\; I} = \frac{1}{{{L^{*}({black})} - {L^{*}({white})}}}} & (3)\end{matrix}$

where L*(black) and L*(white) are the measured lightness or L* value ona black and white background, respectively. Full opacity is obtainedwhen L*(black) is equivalent to L*(white) causing the hiding power indexto equate to infinity. The HPI associated with this pigment is listed inTable 7.

TABLE 7 CIE Lab values measured for Examples 8 and 9 using a 10°observer and D65 illuminant with specular component included. Pigmentdrawdowns (3 mil Bird applicator) were prepared by dispersing 0.75 gpigment in 5 g of vehicle (10% CAB 531-1 (Eastman Chemical) in n-butylacetate). Reaction Final White Background Black Background Fe/PigmentInterference L* a* b* Hue L* a* b* Hue Example Ratio (g/g) Color HPIvalue value value Chroma Angle value value value Chroma Angle SunPearl 0Transparent 0.078 92.8 −2.3 5.6 6.0 112.5 79.9 −12.7 −6.0 14.0 205.1Iridescent Green Green 8 0.055 Semi- 1.56 61.9 −10.2 20.1 22.6 116.861.3 −11.7 19.4 22.6 121.1 Opaque Green 9 0.110 Opaque 50.0 48.3 5.822.8 23.5 75.7 48.3 5.6 22.7 23.4 76.0 Gold

TABLE 8 Total composition of Fe (II) and Fe (III) measured for Examples8 and 9. Total Fe Fe (II) Fe (III) Fe (II)/Total Fe Fe (III)/TotalExample (g/g) (g/g) (g/g) (g/g) Fe (g/g) 4 0.065 0.01 0.055 0.15 0.85 50.107 0.017 0.09 0.16 0.84

Example 9 Lustrous, Opaque Gold Pearlescent Pigment

An intensely colored, gold pearlescent pigments with increased opacityrelative to Example 8, was prepared according to the procedure forExample 8 except that the Fe/Pigment mass ratio used in deposition wasincreased by two-fold resulting in higher weight fraction of Fe in thefinal pigment (see Tables 7 and 8). As shown by the CIELAB values listedin Table 7, a vibrantly colored gold pearlescent pigment was obtainedfollowing hydrogenation. The resulting pigment has higher opacity, orhigher hiding power index relative to Example 8 (50.0 compared to 1.56for Example 3) as shown in Table 7.

The progression of the interference color of TiO₂-coated platelet likesubstrates and the opacity may be precisely controlled by the Fe/pigmentmass ratio. As will be shown in the following examples, the two-stepprocess (coating and reduction) may be applied to TiO₂ coated micapigments with various interference colors such as: gold, red, violet,blue, green, and silver. An infinite number of lustrous, coloredpearlescent pigments that span all four quadrants of the CIELAB colorcoordinate system may be produced while controlling the opacity to suitthe intended application.

The color and opacity is directly controlled by the thickness of boththe initial TiO₂ and the deposited FeOOH layers. For semi-opaque shades(as described in Example 8), the reduction of thin FeOOH layers resultin pigments characterized by a simple progression of the initialinterference color or hue angle as shown in Table 7. Reduction ofthicker FeOOH layers results in further advancement of the interferencecolor or hue angle and can progress the interference color to the nextshade (in the case of Example 5, from green to yellow) while increasingthe opacity or HPI.

Examples 10 Through 13 Development of Lustrous, Pearlescent PigmentsUsing TiO₂-Coated Mica with a Gold Interference Color

The methods described above may be applied to TiO₂-coated micasubstrates characterized by a yellow or gold interference color.Examples 10 and 11 are analogous to 6 and 7, except that that thesubstrate material used was SunPearl Iridescent Gold (10-60 μm) ratherthan SunPearl Iridescent Green. The composition of the reaction solutionfor both Example 10 and 11 is shown in Table 6 with the CIELAB values ofthe resulting pigments given in Table 9.

As shown previously, FeOOH deposition results in clockwise advancementof the hue angle (over a black background) of the starting substrate(see Table 9). The initial gold interference color (hue angle=93.4) isadvanced to orange gold (Example 6, hue angle=68.6) at low Fe loadingand further to pink (hue angle=24.2) at increased FeOOH layer thickness.Following deposition, these pigments are goniochromatic, orcharacterized by a specific interference color (in this case, orange,gold, or pink) at some viewing angles, with a gold to yellow absorbancecolor at others. The gold to yellow absorbance color is due to theprecipitated yellow iron oxide or FeOOH layer. As the FeOOH thicknessincreases, the darkness of the coated pigment increases as shown by themeasured L* values depicted in Table 9.

The reduction of Examples 10 and 11 by the hydrogenation methoddescribed in Example 8, yielded Examples 12 and 13, respectively.Example 12 is a lustrous semi-opaque, orange pigment with a HPI of0.267. Due to the relatively thin FeOOH layer, reduction resulted in asmall advancement of the hue angle, shifting the interference color fromgold to orange. Although the conditions for reduction between Examples12 and 13 were equivalent, Example 13 yields a more opaque (HPI=1.099),darker, lustrous plum pigment. The larger color shift, from a hue angleof 49.2 (Example 12 on a black background) to 354.7 (Example 13 on ablack background), and the increase in opacity is due to the increasedthickness of the coated FeOOH layer.

TABLE 9 CIE Lab values measured for Examples 10-13 using a 10° observerand D65 illuminant with specular component included. Pigment drawdowns(3 mil Bird applicator) were prepared by dispersing 0.75 g pigment in 5g of vehicle (10% CAB 531-1 (Eastman Chemical) in n-butyl acetate).Reaction Final White Background Black Background Fe/Pigment InterferenceL* a* b* Hue L* a* b* Hue Example Ratio (g/g) Color HPI value valuevalue Chroma Angle value value value Chroma Angle SunPearl 0 Transparent0.094 93.3 −1.3 9.6 9.69 97.9 82.59 −1.0 17.6 17.6 93.4 Iridescent GoldGold 10 0.055 Transparent 0.118 76.8 16.2 46.8 49.6 70.9 68.4 14.3 36.439.1 68.6 Orange- Gold 11 0.110 Transparent 0.091 67.0 26.7 29.1 39.547.5 56.0 24.2 10.9 26.5 24.2 Pink 12 0.055 Semi- 0.267 59.6 28.9 34.845.2 50.3 55.9 25.6 29.7 39.2 49.2 Opaque Orange 13 0.110 Semi- 1.09937.9 15.6 −0.5 15.6 358.0 37.0 14.9 −1.4 15.0 354.7 Opaque Plum

Examples 14 Through 19 Development of Lustrous, Pearlescent PigmentsUsing TiO₂-Coated Mica with a Red Interference Color

Examples 14 through 19 were prepared according to the proceduredescribed in Example 6, except that the TiO₂-coated mica substrates(SunPearl Iridescent Red, 10-60 μm) were characterized by a pink to redinterference color. The reaction Fe/Pigment mass ratios used areindicated in Table 6. The CIELAB values for each pigment prepared areshown in Table 10.

For clarity, the a* and b* coordinates of Examples 14-16 measuredagainst a black background are plotted in FIG. 1. Pigment drawdowns (3mil Bird applicator) of Examples 14-16 were prepared by dispersing 0.75g pigment in 5 g of vehicle (10% CAB 531-1 (Eastman Chemical) in n-butylacetate). FIG. 1 shows that deposition at very low Fe/pigment ratios, inparticular for Fe/pigment ratios less than about 0.055, results in aninitial increase in the b* coordinate with small impact on the a* value.This is perhaps due to the characteristic yellow absorbance of FeOOH. Itis from this point, point 2 in FIG. 1, that the clockwise shift in hueangle begins at increasing FeOOH layer thickness. As shown, the hueangle begins to progress pass the initial hue angle of the supportmaterial at Fe/pigment ratios of about 0.055. For Example 16 (Fe/pigmentratio=0.055), the interference color is noticeably violet indicatingsufficient progression to the next shade (red to violet).

The reduction of Examples 14-16 by the hydrogenation method described inExample 8, yielded Examples 17-19, respectively. As shown by the CIELABvalues depicted in Table 10, reduction yields lustrous, pearlescentpigments ranging from pink to light violet, and the hiding power index,or HPI, associated with these pigments increased with increasingFe/pigment mass ratio.

TABLE 10 CIE Lab values measured for Examples 14-19 using a 10° observerand D65 illuminant with specular component included. Pigment drawdowns(3 mil Bird applicator) were prepared by dispersing 0.75 g pigment in 5g of vehicle (10% CAB 531-1 (Eastman Chemical) in n-butyl acetate).Reaction Final White Background Black Background Fe/Pigment InterferenceL* a* b* Hue L* a* b* Hue Example Ratio (g/g) Color HPI value valuevalue Chroma Angle value value value Chroma Angle SunPearl 0 Transparent0.047 91.9 1.14 4.36 4.51 75.3 70.7 17.3 −6.6 18.5 339.3 IridescentPink/Red Red 14 0.01375 Transparent 0.069 83.2 11.9 21.6 24.7 61.2 68.817.3 3.0 17.5 9.8 Pink 15 0.0275 Transparent 0.073 79.4 17.0 21.1 27.151.0 65.7 18.7 1.6 18.8 4.8 Pink 16 0.055 Transparent 0.059 70.7 23.112.7 26.4 28.8 53.7 19.1 −14.5 24.0 322.8 Pink-Violet 17 0.01375Transparent 0.068 72.6 23 15.3 27.6 33.6 58.0 26.2 −4.9 26.6 349.4 Pink18 0.0275 Transparent 0.095 63.4 31.5 9.5 32.9 16.8 52.9 27.8 −6.9 28.7346.2 Pink 19 0.055 Semi- 0.305 47.7 18.2 −12.9 22.3 324.6 44.4 18.4−17.4 25.3 316.6 Opaque Light Violet

Examples 20 Through 23 Development of Lustrous, Pearlescent PigmentsUsing TiO₂-Coated Mica with a Violet Interference Color

Examples 20 and 21 were prepared according to the procedure described inExample 6, except the TiO₂-coated mica substrate had a violetinterference color (SunPearl Iridescent Violet, 10-60 μm), and usedreaction Fe/pigment ratios of 0.055 and 0.110, respectively as shown inTable 6. The CIELAB values for the pigments following FeOOH depositionare given in Table 11.

TABLE 11 CIE Lab values measured for Examples 20-23 using a 10° observerand D65 illuminant with specular component included. Pigment drawdowns(3 mil Bird applicator) were prepared by dispersing 0.75 g pigment in 5g of vehicle (10% CAB 531-1 (Eastman Chemical) in n-butyl acetate).Reaction Final White Background Black Background Fe/Pigment InterferenceL* a* b* Hue L* a* b* Hue Example Ratio (g/g) Color HPI value valuevalue Chroma Angle value value value Chroma Angle SunPearl 0 Transparent0.047 91.2 1.4 2.5 2.9 60.2 69.7 17.7 −16.7 24.3 316.7 Iridescent VioletViolet 20 0.055 Transparent 0.064 74.9 16.7 12.6 20.9 37.07 59.3 6.1−13.1 14.5 295.0 Violet 21 0.110 Transparent 0.096 72.8 8.6 21.6 23.368.4 62.4 −11.4 4.3 12.2 159.4 Blue 22 0.055 Semi- 0.532 44.2 3.9 −21.121.5 280.4 42.3 2.0 −23.9 24.0 274.8 Opaque Dark Violet 23 0.110 Opaque4.762 43.5 −10.4 −5.5 11.8 208.0 43.3 −10.8 −6.04 12.4 209.24 Dark Blue

The pigments of Examples 20 and 21 displayed the characteristicclockwise shift in hue angle, resulting in the gradual progression froma violet to blue interference color at increased Fe/pigment ratio. Thereduction of Examples 20 and 21, using the conditions described inExample 8, yielded Examples 22 and 23, respectively. As shown in Table11, the reduction of thin FeOOH surface layers (such as Example 22)yields a semi-opaque pearlescent pigment characterized by a colorsimilar to the interference color of the TiO₂-coated mica support. Inthis case, Example 22 yields a lustrous, dark violet pearlescentpigment. Reduction of thicker FeOOH layers, such as the pigment producedin Example 23, results in an advancement of the interference color tothe next shade (in this case from violet to blue) and increased opacityor HPI.

Examples 24 Through 27 Development of Lustrous, Pearlescent PigmentsUsing TiO₂-Coated Mica with a Blue Interference Color

Examples 24 and 25 were prepared according to the procedure described inExample 6, except the TiO₂-coated mica substrate had a blue interferencecolor (SunPearl Iridescent Blue, 10-60 μm), and used reaction Fe/pigmentratios of 0.055 and 0.110, respectively, as shown in Table 6. The CIELABvalues are given in Table 12.

TABLE 12 CIELAB values measured for Examples 24-27 using a 10° observerand D65 illuminant with specular component included. Pigment drawdowns(3 mil Bird applicator) were prepared by dispersing 0.75 g pigment in 5g of vehicle (10% CAB 531-1 (Eastman Chemical) in n-butyl acetate).Reaction Final White Background Black Background Fe/Pigment InterferenceL* a* b* Hue L* a* Hue Example Ratio (g/g) Color HPI value value valueChroma Angle value value b* value Chroma Angle SunPearl 0 Transparent0.053 92.2 −1.0 0.9 1.3 137.5 73.2 −7.1 −22.5 23.6 252.5 Iridescent BlueBlue 24 0.055 Transparent 0.103 76.7 5.9 15.7 16.8 69.37 67.0 −15.8 −0.215.8 180.6 Blue 25 0.110 Transparent 0.173 71.4 5.6 35.3 35.7 81.1 65.6−9.51 25.9 27.6 110.2 Green Gold 26 0.055 Semi- 0.520 60.3 −8.5 1.2 8.6171.7 58.4 −17.0 −3.4 17.4 191.3 Opaque Turquoise 27 0.110 Opaque Olive2.170 49.5 −9.9 13.4 16.6 126.4 49.1 −10.1 12.8 16.3 128.4 Green

The pigments of Examples 24 and 25 displayed the characteristicclockwise shift in hue angle resulting in the gradual progression from ablue to green interference color at increased Fe/pigment ratio. Thereduction of Examples 24 and 25, using the conditions described inExample 6 yielded Examples 26 and 27, respectively. As shown in Table12, the reduction of thin FeOOH surface layers (such as Example 26)yields a semi-opaque pearlescent pigment characterized by a colorsimilar to the interference color of the TiO₂-coated mica support. Inthis case, Example 26 yields a lustrous, turquoise pearlescent pigment.Reduction of thicker FeOOH layers, such as the pigment produced inExample 27, results in an advancement of the interference color to thenext shade (in this case from an iridescent blue to opaque olive green)and increased opacity or HPI.

The examples described above indicate that an almost infinite number oflustrous, vibrant colored pearlescent shades with controlled opacity maybe prepared by the methods described herein. The potential color rangespans the CIELAB color space.

Examples 28 Through 31 Development of Lustrous, Pearlescent PigmentsUsing TiO₂-Coated Mica with a Silver Interference Color

Examples 28 and 29 were prepared according to the procedure described inExample 6, except the TiO₂-coated mica substrate had a silverinterference color (SunPearl Silver White, 10-60 μm), and usedFe/pigment ratios of 0.055 and 0.110, respectively, as shown in Table13. The CIELAB values are given in Table 14.

TABLE 13 Quantity of reagents used for FeOOH deposition oncommercially-available TiO₂-coated natural mica substrates. InitialReaction Solution Composition Example Substrate Brand Name Pigment (g)45 wt % FeCl₃ (g) Urea (g) 0.1 M HCl (g) 28 SunPearl Silver White 4014.2 96 706.2 29 SunPearl Silver White 40 28.4 192 706.2

TABLE 14 CIELAB values measured for Examples 28-31 using a 10° observerand D65 illuminant with specular component included. Pigment drawdowns(3 mil Bird applicator) were prepared by dispersing 0.75 g pigment in 5g of vehicle (10% CAB 531-1 (Eastman Chemical) in n-butyl acetate).Reaction Final White Background Black Background Fe/Pigment InterferenceL* a* b* Hue L* a* b* Hue Example Ratio (g/g) Color HPI value valuevalue Chroma Angle value value value Chroma Angle SunPearl 0 Transparent0.136 93.0 −0.1 3.6 3.6 91.2 85.6 −1.5 −2.4 2.9 237.8 Silver SilverWhite 28 0.055 Transparent 0.232 85.4 6.3 21.5 22.4 73.6 81.0 0.6 14.714.7 87.8 Gold-Silver 29 0.110 Transparent 0.376 78.1 8.8 28.5 29.8 72.975.5 3.9 24.6 25.0 81.1 Gold 30 0.055 Semi- 0.862 76.7 6.4 21.7 22.673.5 75.6 4.4 19.9 20.4 77.5 Opaque Champagne 31 0.110 Opaque 1.852 61.91.8 12.6 12.8 81.9 61.4 1.5 12.2 12.3 83.11 Metallic Grey

As shown in Table 14, FeOOH deposition results in a transition from atransparent silver white to golden shades. The deposition of thickerFeOOH layers results in a more golden color and a noticeably darkerappearance (lower L* value). The reduction of Examples 28 and 29, usingthe conditions described in Example 8 yielded Examples 30 and 31,respectively. Example 30 is a lustrous, semi-opaque, champagne-coloredpearlescent pigment with a HPI of 0.862. At increased reactionFe/pigment mass ratio, as used in Example 31, gave a more opaque(HPI=1.852), metallic grey pearlescent pigment with a darker appearance(lower L* value, see Table 14).

Example 32 Alkaline Stability Testing—Blue Pearlescent Pigments

Example 23 and six commercially available blue pearlescent pigments weretested for alkaline stability. The samples tested and theircorresponding components are listed in Table 15.

TABLE 15 Pigment samples tested for alkaline (pH 12.5) stability.Particle Size Product Range Sample Supplier Code Composition (μm)Example 23 Sun Mica, TiO₂, Fe₃O₄ 10-60  Chemical Duocrome ® BY Engelhard226C Mica, TiO₂, Iron Blue 6-50 Duocrome ® BR Engelhard 426C Mica, TiO₂,Iron Blue 6-50 Duocrome ® BV Engelhard 526C Mica, TiO₂, Iron Blue 6-50Duocrome ® BG Engelhard 826C Mica, TiO₂, Iron Blue 6-50 Cosmica ® BlueEngelhard MCB27 Mica, Iron Blue 6-48 Cloisonné ® Engelhard 626C Mica,TiO₂, Iron Blue 6-48 Blue

A basic solution (pH 12.5, NaOH in distilled water) was mixed with 2 wt% pigment (see Table 15) to prepare suspensions. The suspensions weremixed, and allowed to settle for about 5 hours. The pigments were thenfiltered, rinsed with deionized water, and dried at 80° C.

Pigment drawdowns (3 mil Bird applicator) were prepared by dispersing0.5 g of each pigment in 4.5 g of vehicle (PPG Delstar DMR499AcrylicEnamel), followed by applying the mixture to a Leneta Form 2C opacitycard. The CIELAB color coordinates (100 observer and D65 illuminant withspecular component included) for the treated and untreated samples weremeasured using a Spectraflash SF600 Plus spectrophotometer at a 90°viewing angle. The hiding power index (before and after treatment) andcolor difference or ΔE* (ΔE*=((ΔL*)²+(Δa*)²+(Δb*)²)^(1/2)) between thetreated and untreated samples were measured against a black and whitebackground, see Table 16.

TABLE 16 Hiding power index (HPI) and color difference values (ΔE*) forblue pearlescent pigment samples before and after alkaline treatment (pH12.5, 5 hours). ΔE* (Treated vs Untreated) HPI HPI White Black Sample(Untreated) (Treated) Background Background Example 23 0.469 0.408 1.711.40 Duocrome ® BY 0.294 0.068 39.66 21.82 Duocrome ® BR 0.110 0.03646.01 15.29 Duocrome ® BV 0.091 0.033 50.75 13.26 Duocrome ® BG 0.3150.063 45.99 20.84 Cosmica ® Blue 0.649 0.119 14.23 2.79 Cloisonné ®0.169 0.039 56.50 16.94 Blue

All the commercially available blue pearlescent pigments testeddisplayed a marked shift in color and opacity following immersion inalkaline solution. The measured color difference is due to theinstability of iron blue in alkaline environment. The absence of ironblue or ferric ferrocyanide in the preparation of blue pearlescentpigments represents a significant advantage in terms of alkalinestability. For the blue pearlescent pigment prepared as described inExample 23, the treated and untreated samples showed a small relativecolor difference (ΔE*<2) with a marginal drop in opacity (HPI drop from0.469 to 0.408).

Example 33 Acid Stability Testing—Red/Pink Pearlescent Pigments

Example 18 and six commercially available red/pink mica basedpearlescent pigments were tested for acid stability. The samples testedand their corresponding components are listed in Table 17.

TABLE 17 Pigment samples tested for acid (pH 1.5) stability. ParticleSize Product Range Sample Supplier Code Composition (μm) Example 18 SunMica, TiO₂, Fe₃O₄ 10-60  Chemical Duocrome ® RY Engelhard 224C Mica,TiO₂, 6-50 Carmine Duocrome ® RO Engelhard 324C Mica, TiO₂, 6-50 CarmineDuocrome ® RV Engelhard 524C Mica, TiO₂, 6-50 Carmine Gemtone ® RubyEngelhard G010 Mica, TiO₂, Iron 6-48 Oxide, Carmine Cloisonné ® RedEngelhard 424C Mica, TiO₂, 6-48 Carmine Cloisonné ® Nu Engelhard 424CBMica, TiO₂, Iron 6-48 Antique Red Oxides, Carmine Cosmica ® RedEngelhard MCNR4 Mica, Carmine 6-48

An acidic solution (pH 1.5 of concentrated HCl in distilled water) wasmixed with 2 wt % pigment (see Table 17) to prepare a suspension. Thesuspensions were mixed, and allowed to settle for about 20 hours. Thepigments were filtered, rinsed with deionized water and dried at 80° C.

Drawdown preparation and color analysis was performed as described inthe previous example. The hiding power index (before and aftertreatment) and color difference or ΔE* between the treated and untreatedsamples measured against a black and white background is shown in Table18.

As shown in Table 18, the pink pearlescent pigment of Example 18 showedthe lowest color difference (or lower ΔE*) against a white backgroundfollowing exposure to acidic conditions. Only the Cosmica® Red showedlower ΔE* measured against a black background. This low value of ΔE*measured for the Cosmica® Red sample is due to the similarity of its L*value (L*=27.25) with that of the black background (L*=27.20) as shownin Table 19. In reality, the Cosmica® Red sample showed significantdegradation as is evident by its marked change in color coordinatesmeasured against a white background as depicted in Table 20(ΔE*=16.258).

TABLE 18 Hiding power index (HPI) and color difference values (ΔE*) forred pearlescent pigment samples before and after acid treatment (pH 1.5,20 hours). ΔE* (Treated vs Untreated) HPI HPI White Black Sample(Untreated) (Treated) Background Background Example 18 0.063 0.058 3.0241.589 Duocrome ® RY 0.159 0.120 12.068 7.944 Duocrome ® RO 0.098 0.06917.154 7.753 Duocrome ® RV 0.060 0.047 17.615 5.524 Gemtone ® Ruby 0.2540.225 3.935 2.609 Cloisonné ® Red 0.077 0.061 15.263 6.402 Cloisonné ®Nu 1.111 0.546 3.311 2.097 Antique Red Cosmica ® Red 0.066 0.035 16.2581.432

TABLE 19 CIE Lab values measured against a black background using a 10°observer and D65 illuminant with specular component included. Pigmentdrawdowns (3 mil Bird applicator) were prepared by dispersing 0.5 gpigment in 4.5 g of vehicle (PPG Delstar DMR499 Acrylic Enamel).Untreated Pigment Treated Pigment (pH 1.5, 20 hr) L* a* b* Hue L* a* b*Hue Sample value value value Chroma angle value value value Chroma angleExample 18 45.80 23.5 −9.39 25.31 338.22 46.45 24.54 −8.38 25.94 341.15Duocrome ® 64.52 9.67 16.08 18.76 58.99 68.58 4.1 20.03 20.45 78.43 RYDuocrome ® 56.84 19.45 10.75 22.23 28.93 60.79 14.3 14.99 20.71 46.35 RODuocrome ® 46.73 24.7 −30.39 39.17 309.11 49.61 21.08 −27.37 34.55307.61 RV Gemtone ® 45.79 29.83 0.00 29.83 360 47.42 28.35 1.4 28.382.83 Ruby Cloisonné ® 49.2 29.66 −10.24 31.38 340.96 52.74 26.01 −6.3526.78 346.29 Red Cloisonné ® Nu 35.83 14.82 −6.35 16.12 336.78 37.5314.45 −5.18 15.35 340.28 Antique Red Cosmica ® Red 27.25 4.14 0.97 4.2513.19 27.08 3.11 −0.01 3.11 359.74

In addition to improved color consistency in the dry form, the pigmentof Example 18 was the only sample that showed no signs of colorantbleeding into the acidic solution. Following filtration of the acidicsuspensions, the filtrate was analyzed in the visible region forcolorant bleeding (see FIG. 2). As shown in FIG. 2, the pigment preparedby the current invention was the only filtrate sample that showed nosignificant absorption in the visible region. All acidic suspensionscontaining commercial pigments were red in appearance indicative of theinstability of carmine colorants in acidic environments.

TABLE 20 CIE Lab values measured against a white background using a 10°observer and D65 illuminant with specular component included. Pigmentdrawdowns (3 mil Bird applicator) were prepared by dispersing 0.5 gpigment in 4.5 g of vehicle (PPG Delstar DMR499 Acrylic Enamel).Untreated Pigment Treated Pigment (pH 1.5, 20 hr) L* a* b* Hue L* a* b*Hue Sample value value value Chroma angle value value value Chroma angleExample 18 61.58 29.44 14.81 32.95 26.7 63.62 29.33 17.04 33.92 30.16Duocrome ® 70.81 20.76 9.54 22.85 24.69 76.88 11.65 14.62 18.69 51.46 RYDuocrome ® 67.01 28.73 4.68 29.11 9.25 75.25 15.81 12.39 20.09 38.09 RODuocrome ® 63.3 33.47 −13.04 35.92 338.72 71.02 21.26 −2.96 21.47 352.07RV Gemtone ® 49.72 35.65 4.98 36 7.94 51.87 33.32 7.31 34.11 12.37 RubyCloisonné ® 62.18 36.82 −4.23 37.06 353.45 69.17 25.95 3.89 26.24 8.52Red Cloisonné ® Nu 36.73 15 −6.11 16.2 337.83 39.36 13.88 −4.44 14.57342.26 Antique Red Cosmica ® Red 42.47 47.18 2.3 47.23 2.8 55.75 38.070.07 38.07 0.11

Example 34 Alkaline Stability Testing—Green Pearlescent Pigments

Example 27 and three commercially available green mica based pearlescentpigments were tested for alkaline stability. The samples tested andtheir corresponding components are listed in Table 21.

TABLE 21 Pigment samples tested for alkaline (pH 12.5) stability.Particle Size Product Range Sample Supplier Code Composition (μm)Example 27 Sun Mica, TiO₂, Fe₃O₄ 10-60  Chemical Cloisonné GreenEngelhard 828C Mica, TiO₂, Cr₂O₃ 6-48 Cloisonné Blue Engelhard 728CMica, TiO₂, Cr₂O₃ 6-48 Green Cloisonné Nu Engelhard 828CB Mica, TiO₂,Cr₂O₃, 6-48 Antique Green Iron Oxides

A basic solution (pH 12.5, NaOH in distilled water) was mixed with 2 wt% pigment (see Table 21) to prepare suspensions. The suspensions weremixed, and allowed to settle for about 55 hours. The pigments were thenfiltered, rinsed with deionized water, and dried at 80° C.

Drawdown preparation and color analysis was performed as described inExample 32. The hiding power index (before and after treatment) andcolor difference or ΔE* between the treated and untreated samplesmeasured against a black and white background is shown in Table 22.

TABLE 22 Hiding power index (HPI) and color difference values (ΔE*) forgreen pearlescent pigment samples before and after alkaline treatment(pH 12.5, 55 hours). ΔE* (Treated vs Untreated) HPI HPI White BlackSample (Untreated) (Treated) Background Background Example 27 0.5050.417 2.49 1.78 Cloisonné Green 0.099 0.107 0.36 0.64 Cloisonné Blue0.099 0.087 1.64 0.69 Green Cloisonné Nu 1.351 0.329 16.68 14.14 AntiqueGreen

Table 21 consists of three types of green pearlescent pigments:Mica-TiO₂+Cr₂O₃ Cloisonné Green and Blue Green), Mica-TiO₂+Cr₂O₃ mixedwith iron oxide particles (Cloisonné Nu Antique Green) and Example 27. Adifference between the pigment of Example 27 and the commerciallyavailable green pearlescent pigments shown in Table 21 is the absence ofCr₂O₃. Freedom from chromium containing compounds allows for the use ofthose green pearlescent pigments in more cosmetic compositions,specifically in applications involving the lip area.

As shown in Table 22, the color stability in alkaline environments ofthe green pearlescent pigment (ΔE*=2.49 over a white background andΔE*=1.78 over a black background) described in example 27 is consistentwith values observed for the blue pearlescent pigment (ΔE*=1.71 over awhite background and ΔE*=1.40 over a black background) described inexamples 23 and 32.

In addition to being chromium-free, the green pearlescent pigmentsdescribed may be made in both transparent (low HPI) and opaque (highHPI) varieties. TiO₂-coated mica pigments containing a layer of Cr₂O₃are generally restricted to transparent pearlescent pigments as depictedin Table 22 (HPI=0.099). On the other hand, Example 27 is much moreopaque (HPI=0.505) than both the Cloisonné Green and Blue Green. This issignificant when considering that the particle size distribution forExample 27 is slightly higher (see Table 21) than the Cloisonné seriespigments. This property allows a more lustrous, green pearlescentpigment with improved hiding power or opacity compared to Cr₂O₃ coatedmica-based pigments.

In order to improve hiding power or opacity, conventional Cr₂O₃ coatedmica-based pigments can be combined with loose iron oxide particles tocreate opaque green pearlescent pigments, such as the technique used toprepare Cloisonné Nu Antique Green (see Table 21). As shown in Table 22,this results in a significant increase in hiding power or surfacecoverage (HPI=1.351). However, a significant drawback of this approachis the loss of luster due to excess light scattering and the generaldirty appearance that results from the presence of these loosenonplatelet-like particles. This approach also results in a significantpresence of color stability in liquid preparations (as depicted by thehigh ΔE* shown in Table 22) due to separation of the loose iron oxideparticles from the Cr₂O₃ coated mica-based pigment.

Example 35 Semi Transparent, Carmine-Free, Red Pearlescent Pigments

Five carmine-free and seven carmine containing red pearlescent pigmentswere compared, see Table 23. The color of the drawdown of the pigmentswere red, and had a hue angle from not less than about 275 to not morethan about 50 degrees. Drawdown preparation and color analysis wasperformed as described in example 32. The CIELAB color coordinates andthe hiding power index for each sample is depicted in Table 24. Thepearlescent pigment of example 18 was the only red pearlescent pigmentthat does not contained carmine with a HPI less than about 1.

TABLE 23 Red Pearlescent Pigments Contains Sample Pigment SupplierCarmine 1 Example 18 SunChemical N 2 Duocrome ® RY Engelhard/BASF Y 3Duocrome ® RO Engelhard/BASF Y 4 Duocrome ® RV Engelhard/BASF Y 5Gemtone ® Ruby Engelhard/BASF Y 6 Cloisonné ® Red Engelhard/BASF Y 7Cloisonné ® Nu Antique Red Engelhard/BASF Y 8 Cosmica ® RedEngelhard/BASF Y 9 Xirona ® Le Rouge Merck N 10 Sunshine Super RussetSunChemical N 11 SunPearl Maroon SunChemical N 12 SunPearl BronzeSunChemical N

TABLE 24 HPI of Red Pearlescent Pigments White Background BlackBackground L* a* b* Hue L* a* b* hue Sample HPI value value value Chromaangle value value value Chroma angle 1 0.063 61.58 29.44 14.81 32.9526.7 45.8 23.5 −9.39 25.31 338.22 2 0.159 70.81 20.76 9.54 22.85 24.6964.52 9.67 16.08 18.76 58.99 3 0.098 67.01 28.73 4.68 29.11 9.25 56.8419.45 10.75 22.23 28.93 4 0.060 63.3 33.47 −13.04 35.92 338.72 46.7324.7 −30.39 39.17 309.11 5 0.254 49.72 35.65 4.98 36 7.94 45.79 29.83 029.83 360 6 0.077 62.18 36.82 −4.23 37.06 353.45 49.2 29.66 −10.24 31.38340.96 7 1.111 36.73 15 −6.11 16.2 337.83 35.83 14.82 −6.35 16.12 336.788 0.066 42.47 47.18 2.3 47.23 2.8 27.25 4.14 0.97 4.25 13.19 9 2.56444.73 40.17 19.61 44.7 26.01 44.34 39.48 19.04 43.83 25.74 10 1.61346.02 31.33 12.63 33.78 21.96 45.4 29.5 11.4 31.63 21.12 11 1.099 45.6132.23 16.17 36.06 26.64 44.7 29.79 14.54 33.15 26.02 12 3.704 61.9818.38 27.52 33.09 56.26 61.71 16.95 26.98 31.86 57.86

Example 36 Clear Gel Lip Gloss Preparation

The constituents of the clear gel lip gloss base shown in Table 25 aremixed homogeneously and heated to 80° C. Following sufficient cooling toroom temperature, the pigment from Example 8 was added at 2 wt % to thebase gel and mixed thoroughly. Similar lip gloss preparations usedpigments from Examples 18, 19, 23, 24, 25, 27 and 31.

TABLE 25 Composition of clear gel lip gloss base. Ingredients WeightFraction (%) Versagel ME750 (Penreco) 81.5 Ceraphyl 368 (Sblack, ISP) 10Ceraphyl 55 (ISP) 5 Isostearyl Isostearate (Mosselman) 3 Germaben(Clariant) 0.5

Prophetic Example 47 Nail Varnish

The cosmetic composition of a nail lacquer comprising a pearlescentpigment may be prepared from the components set forth in the Tablebelow.

Amount Components (%) Nail polish base 94 (Kirker Enterprises, Inc. ofPatterson, NJ) pearlescent pigment 6 Total 100

Prophetic Example 48 Lipstick

The cosmetic composition of a lipstick comprising a pearlescent pigmentmay be prepared from the components set forth in the Table below.

Amount Components (g) Octyldodecyl ricinoleate 10.2 Castor oil 18Tridecyl trimellitate 3 Octyldodecanol 4 Tridecyl trimellitate 3 Lanolinwax 6 Lanolin oil 6 Hydrogenated cocoglycerides 5 Acetylated lanolin 3Hydrogenated milk glycerides 5 Pentaerythritylk 4 tetraisononanoateOzokerite wax 5 Candelilla wax 5 Carnauba wax 1 Synthetic wax 3Butylated hydroxyanisole 0.5 Propylparaben 0.15 FD&C Yellow 6 (1:2 7.5aluminum lake castor oil dispersion) Black iron oxide castor oil 0.6dispersion (1:2) Red iron castor oil dispersion 2 (1:2) pearlescentpigment 8 Total 99.95

Prophetic Example 49 Lip Gloss

The cosmetic composition of a lip gloss comprising a pearlescent pigmentmay be prepared from the components set forth in the Table below.

Amount Components (g) Hydroxystearic acid 1.46 Trimethylolpropane 10.93triisostearate Polybutene 59 Mineral oil 5.37 Isocetyl stearate 8.02Diisostearyl malate 8.38 FD&C Blue 1 (aluminum 0.01 lake) D&C Red 7(calcium lake) 0.02 Polyethylene tetrephthalate 0.2 pearlescent pigment8 Total 101.39

Prophetic Example 50 Mascara

The cosmetic composition of a mascara comprising a pearlescent pigmentmay be prepared from the components set forth in the Table below.

Amount Components (g) Petroleum Distillate 68 Polyethylene 12Dihydroabietyl alcohol 5 Candelilla wax 2.4 Aluminum stearate 0.05Butylparaben 0.1 Black iron oxide 4 pearlescent pigment 8 Total 99.55

Prophetic Example 51 Face Powder

The cosmetic composition of a face powder comprising a pearlescentpigment may be prepared from the components set forth in the Tablebelow.

Amount Components (g) Iron oxide 6.57 Zinc stearate 4 Titanium dioxide 2Bismuth oxychloride 10 Nylon powder sold under the 20 name “ORGASOL ®”by the company ATOCHEM Vaseline oil 3.26 Oleyl alcohol 0.6 Isopropylmyristate 0.43 Propyl para-hydroxybenzoate 0.12 pearlescent pigment 3Talc qs. 100 Total 149.98

Prophetic Example 52 Eye Shadow

The cosmetic composition of a eye shadow comprising a pearlescentpigment may be prepared from the components set forth in the Tablebelow.

Amount Components (%) Talc 49.75 Titanium dioxide 1 Zinc stearate 5 Rediron oxide 0.15 Yellow iron oxide 0.1 Polyethylene 3 Magnanese violet 5Iridescent red nacreous 25 Mineral oil 7 Dimethicone fluid 4 Total 100

Prophetic Example 53 Blush

The cosmetic composition of a blush comprising a pearlescent pigment maybe prepared from the components set forth in the Table below.

Amount Components (g) Zinc stearate 3 Titanium oxide 2 Iron oxide 9 Mica24 Nylon powder sold under the 15 name ORGASO ® by the company ATOCHEMpearlescent pigment 5 Vaseline oil 3.26 Oleyl alcohol 0.6 Isopropylmyristate 0.43 Propyl para-hydroxybenzoate 0.12 Talc qs. 100 Total162.41

Prophetic Example 54 Hair and Body Gel

The cosmetic composition of a hair and body gel comprising a pearlescentpigment may be prepared from the components set forth in the Tablebelow.

Amount Components (%) Deionized water 84 Carbomer 2 pearlescent pigment7.8 Glycerin 2.5 Vinylpyrrolidone/vinyl 2.5 actetate copolymerTriethanolamine 1 Germaben-11 ® 0.2 Total 100

Prophetic Example 55 Lotion

The cosmetic composition of a lotion comprising a pearlescent pigmentmay be prepared from the components set forth in the Table below.

Amount Components (g) Deionized water 79.6 Carbomer 0.5 Polysorbate 0.8Propylene glycol 2 Glycerin 5 Triethanolamine 0.6 pearlescent pigment 2Acetylated lanolin 3 alcohol Cetyl alcohol 2 Stearic acid 5 LiquaPar ®0.5 Total 101

Prophetic Example 56 Foundation

The cosmetic composition of a lipstick comprising a pearlescent pigmentmay be prepared from the components set forth in the Table below.

Amount Components (g) Glycerol stearate 2.2 Triglycerides ofcapric/caprylic 15.0 acids sold under the name “MIGLYOL 812 ®” by thecompany DYNAMIT NOBEL Yellow iron oxides 0.75 Brown iron oxides 0.47Black iron oxide 0.23 Titanium dioxide 4.55 Methyl para-hydroxybenzoate0.1 Propyl para-hydroxybenzoate 0.1 Imidazolidinyl urea 0.32-hydroxy-4-methoxybenzophenone 0.5 Octyl N,N- 0.5dimethylparaaminobenzoate. Pearlescent pigment 3.0 Aluminum andmagnesium silicate 1.0 sold under the name “VEEGUM ®”by the companyVENDERBILT Triethanolamine 1.0 Cellulose gum 0.16 Aluminum salt of theproduct of the 5.0 reaction of octenylsuccinic anhydride with starchsold under the name “DRY FLO ®” by the company NATIONAL STARCHCyclomethicone sold under the 10.0 name “VOLATIL SILICONE 7158 ®” by thecompany UNION CARBIDE Water 47.34 Propylene glycol 2.0 Glycerin 3.0Sodium salt of lauroylsarcosine sold 0.6 under the name “ORAMIX L30 ®”by the company SEPPIC Stearic acid 2.2 Total 100

Example 57 Eye Shadow Cream

Phase A Ingredient wt % Water (q.s to 100%) 64.20% Magnesium 1.00%Aluminum Silicate Xanthan Gum 0.30%

Phase B Ingredient wt % Triethanolamine (TEA 99%) 0.30% Propylene Glycol8.00% Preservative (Water soluble) q.s.

Phase C Ingredient wt % Pearlescent pigment 20.00%

Phase D Ingredient wt % Stearic Acid (Stearic Acid 94%) 4.00% GlycerilStearate 0.80% Oleyl Alcohol 0.50%

Procedure:

Xanthan gum and magnesium aluminum silicate were dispersed intodeionized water using high shear mixing until the mixture was smooth, toform Phase A. Triethanolamine, propylene glycol, and a water solublepreservative were added to the smooth gum mixture of Phase A and mixeduntil smooth. Stearic acid, glyceril stearate, and oleyl alcohol wereheated to 75±5° C. with gentle agitation, to form Phase D.

The pearlescent pigment material was added to the Phase A-B mixture withgentle agitation, and maintained at a temperature of 75±5° C. Phase Dwas added to the Phase A-B-C mixture with gentle agitation, whilemaintaining a temperature of 75±5° C. A constant agitation wasmaintained and the overall mixture was cooled to 35±5° C.

When the Eye Shadow Cream was applied on skin, the following resultswere observed:

Pearlescent pigment Result Example 27 shimmering Olive green shade withgreen and red iridescent sparkling points, depending on the viewingangle

Example 58 Eye Shadow Gel

Phase A Ingredient wt % Water (q.s to 100%) 63.00% Acrylates/C10-30Alkyl  0.30% Acrylate Crosspolymer

Phase B Ingredient wt % Water 13.00%  Glycerin 2.00% Triethanolamine(TEA 99%) 0.70% Preservative (Water Soluble) q.s to 100%

Phase C Ingredient wt % Pearlescent pigment 20.00%

Procedure:

Acrylates/C10-30 alkyl acrylate crosspolymer was dispersed in deionizedwater using high shear mixing until the mixture was smooth. Glycerin,triethanolamine, and water soluble preservative were dispersed in partof the deionized water of Phase B, then added to the mixture of Phase A,and mixed until smooth.

The pearlescent pigment material of Phase C was added to the Phase A-Bmixture with gentle agitation at room temperature.

Both on the container of the eye shadow gel and when it is applied onthe skin, the following results were observed:

Pearlescent pigment Result Example 70 sparkling deep and warm brilliantblack shade with russet and multi-iridescent white, gold, red, violet,blue and green sparkling points, depending on the viewing angle, with avinyl effect Example 25 sparkling metallic gold shade with greeniridescent duocrome effect and small red, green and turquoise sparklingpoints, depending on the viewing angle

Example 59 Pressed Powder

Phase A Ingredient wt % Talc 45-80% (q.s to 100) Dimethicone and 5.00%Dimethicone Crosspolymer Preservatives (q.s to 100)

Phase B Ingredient wt % Pearlescent pigment 15.00-50.00%

Procedure:

Talc, dimethicone and dimethicone crosspolymer, and preservatives werethoroughly blended and dispersed in an appropriate dryblending/dispersing equipment. The pearlescent pigment material of PhaseB was added to the dry blended ingredients and mixed until uniform.

When the opaque Pressed Powder Eye Shadow was applied onto skin, thefollowing color travel results were observed:

Pearlescent pigment Result Example 66 shimmering old bronze-beige veilwith gold, red and green sparkling points, depending on the viewingangle

Example 60 Nail Polish Nail Polish Base:

Ingredient wt % Butyl Acetate 25-50% Ethyl Acetate 10-25% Nitrocellulose10-25% Acetyl Tributyl Citrate  5-10% Phtalic Anhydride/TrimelliticAnhydride/Glycol  5-10% Copolymer Isopropyl Alcohol  5-10% StearalkoniumHectorite 1-5% Adipic Acid/Fumaric Acid/Phtalic 1-5% Acid/TricyclodecaneDimethanol Copolymer Citric Acid <0.1%

Procedure:

Pearlescent pigment (5 parts) was mixed with Nail Polish Base (95 parts)in an appropriate size vessel fitted with a Lightning™ type propellermixer. The components were mixed until uniform.

The following strong color travel results, both in the clear nail enameland in the lacquer, applied to the nail were observed:

Pearlescent pigment Result Example 18 shimmering light yellow-pink shadewith red and violet iridescent sparkling points, depending on theviewing angle Example 28 shimmering silver gold shade with kind of satineffect with white, gold, red and green iridescent sparkling points,depending on the viewing angle Example 31 shimmering “old dark bronze”shade with gold, red and green iridescent sparkling points, depending onthe viewing angle

Example 60 High Gloss Colored Lipstick

Phase A Ingredient wt % Castor Oil (q.s to 100%) 14.56% IsononylIsononanoate 17.51% Pentaerythrityl TetraCaprylate/Tetracaprate 8.75%Octyldodecanol 5.47% Lanolin Oil 11.93% Caprylic/Capric/StearicTriglyceride 7.11% Candelilla Wax 9.30% Carnauba Wax 3.28% PolybuteneH-100 7.66% Ozokerite 2.20% Lanolin Wax 1.09% Red 7 Lake 0.80%Preservative q.s. Antioxidant q.s.

Phase B Ingredient wt % Pearlescent pigment 10.00%

Phase C Ingredient wt % Fragrance 0.10%

Procedure:

Castor oil, isononyl isononanoate, pentaerythrityltetracaprylate/tetracaprate, octyldodecanol, lanolin oil,caprylic/capric/stearic triglyceride, candelilla wax, carnauba wax,polybutene H-100, ozokerite, lanolin wax, red 7 lake, preservative, andantioxidant were all weighed and placed into a heated vessel. Thetemperature was raised to 85±3° C. The ingredients were stirred untilthey were melted and uniform.

The pearlescent pigment of Phase B was dispersed in the castor oil ofPhase A then milled in either a colloid or roller mill. The dispersedpigment was then added and mixed with the remainder of Phase A. Thefragrance of Phase C was then added and mixed with constant stirring.The composition was poured at 75±5° C. then molded, cooled, and flamedinto lipstick.

The following results in the opaque High Gloss Colored Lipstick wereobserved:

Pearlescent pigment Result Example 23 shimmering deep red-violet shadewith intense blue iridescent sparkling points, depending on the viewingangle Example 8 shimmering deep red-bronze shade with red and greeniridescent sparkling points, depending on the viewing angle

Example 61 High Gloss Lipstick

Phase A Ingredient wt % Castor Oil (q.s to 100%) 15.36% IsononylIsononanoate 17.51% Pentaerythrityl TetraCaprylate/Tetracaprate 8.75%Octyldodecanol 5.47% Lanolin Oil 11.93% Caprylic/Capric/StearicTriglyceride 7.11% Candelilla Wax 9.30% Carnauba Wax 3.28% PolybuteneH-100 7.66% Ozokerite 2.20% Lanolin Wax 1.09% Preservative q.s.Antioxidant q.s.

Phase B Ingredient wt % Pearlescent pigment 10.00%

Phase C Ingredient wt % Fragrance 0.10%

Procedure:

Castor oil, isononyl isononanoate, pentaerythrityltetracaprylate/tetracaprate, octyldodecanol, lanolin oil,caprylic/capric/stearic triglyceride, candelilla wax, carnauba wax,polybutene H-100, ozokerite, lanolin wax, preservative, and antioxidantwere all weighed and placed into a heated vessel. The temperature wasraised to 85±3° C. The ingredients were stirred until they were meltedand uniform.

The pearlescent pigment of Phase B was dispersed in the castor oil ofPhase A then milled in either a colloid or roller mill. The dispersedpigment was then added and mixed with the remainder of Phase A.Fragrance from Phase C was then added and mixed with constant stirring.The composition was poured at 75±5° C., then molded, cooled and flamedinto lipstick.

The following results in the opaque High Gloss Lipstick were observed:

Pearlescent pigment Result Example 24 shimmering transparent light beigelipstick with an intense turquoise iridescent sparkling effect,depending on the viewing angle Example 19 shimmering deep violetlipstick with red, blue and violet iridescent sparkling effect,depending on the viewing angle

Example 62 Clear Gel Lip Gloss

Phase A Hydrogenated Polyisobutene and 73.35% Ethylene/Propylene/StyreneCopolymer and Butylene/Ethylene/Styrene Copolymer Ethylhexyl Palmitate9.00% Tridecyl Neopentanoate 4.50% Isostearyl Isostearate 2.70%Preservative q.s.

Phase B Ingredient wt % Pearlescent pigment 10.00%

Procedure:

A pearlescent pigment was prepared as described in Example 6, exceptthat SunPearl Maroon was used in place of SunPearl Iridescent Green. Thepigment was then reduced using the procedure described in Example 8except at a temperature of 200° C. A deep and intensely colored, opaque,plum shade pearlescent pigment was obtained and used as Phase B.

Hydrogenated polyisobutene, ethylene/propylene/styrene copolymer,butylene/ethylene/styrene copolymer, ethylhexyl palmitate, tridecylneopentanoate, isostearyl isostearate, and preservative were all weighedand placed into a heated vessel. The temperature was raised to 50±3° C.The ingredients were stirred until they were melted and uniform. At roomtemperature, pearlescent pigment of Phase B, was added to Phase A andmixed until all the pearlescent pigment was well dispersed. Fragrancemay be added if needed, and mixed with constant stirring. Thecomposition was poured at room temperature.

The following results in the transparent Clear Gel Lip Gloss wereobserved:

Pearlescent pigment Result Phase B intense shimmering dark plum shadevinyl effect lipgloss with red, gold green and turquoise iridescentsparkling effect, depending on the viewing angle

Example 63 Bath and Shower Gel

Phase A Ingredient wt % Water (qs to 100%) 67.80 Acrylates/C10-30 AlkylAcrylate Crosspolymer 0.70 Preservatives q.s. Propylene Glycol 1.00Pearlescent pigment

Phase B Ingredient wt % TEA-Lauryl Sulfate 23.00 Cocamidopropyl Betaine3.50 Cocamide DEA 3.00 Disodium EDTA 0.05

Phase C Ingredient wt % Fragrance 0.20%

Phase D Ingredient wt % Triethanolamine

Procedure:

The acrylates/C10-30 alkyl acrylate crosspolymer were dispersed in waterin a suitable vessel with constant agitation until uniform. Theremainder of the Phase A ingredients were added to the mixture followedby heating the mixture to 65° C. The Phase B ingredients were added oneat a time with constant mixing. The mixture was cooled to 40° C., andthe Phase C & D ingredients were added.

The following results in the Bath and Shower Gel was observed:

Pearlescent pigment Result Example 7 shimmering red gold shade a brightbottle appearance with red, violet and gold iridescent sparkling effect,depending on the viewing angle Example 70 intense shimmering blackbottle appearance with red, gold green to turquoise iridescent sparklingeffect, depending on the viewing angle

Example 64 Color Effect Shampoo

Phase A Ingredients wt % Deionized Water q.s. Acrylates Copolymer (30%)8.00 Sodium Laureth Sulfate (2 mole, 28%) 40.0 Sodium Hydroxide (18%)(q.s. to pH 6.5) 1.50

Phase B Ingredients wt % Cocamidopropyl Betaine (30%) 6.70Polyquaternium 39 (10%) 2.10 Tetrasodium EDTA 0.05 Phenoxyethanol andParabens 0.50

Phase C Ingredient wt % Pearlescent pigment 0.10%

Procedure:

Acrylates copolymer was added to deionized water, followed by sodiumlaureth sulfate with gentle mixing. The pH of the mixture was adjustedto 6.5 with sodium hydroxide. Ingredients of Phase B were added to themixture in order, while mixing. The pH was adjusted to 6.5 with sodiumhydroxide, if necessary. Add Phase C to the mixture with gentle stirringuntil homogeneous.

The following results in the Color Effect Shampoo were observed:

Pearlescent pigment Result Example 7 shimmering red gold shade a brightbottle appearance with red, violet and gold iridescent sparkling effect,depending on the viewing angle Example 70 intense shimmering blackbottle appearance with red, gold green to turquoise iridescent sparklingeffect, depending on the viewing angle

Example 65 Color Effect Styling Gel

Phase A Ingredient wt % Distilled Water (Aqua) q.s. Tetrasodium EDTA0.10 DMDM Hydantoin 0.40 PEG-7M 0.20

Phase B Ingredient wt % Glycerin 1.00 Dimethicone Copolyol 0.20Acrylates/Stearate-20 Itaconate 4.00 Copolymer Triethanolamine) (to pH6.8-7.1) 0.70

Phase C Ingredient wt % PVP 7.00

Phase D Ingredient wt % Pearlescent pigment 5.00%

Procedure:

The ingredients of phase A were mixed in a suitable vessel. Theingredients of Phase B were added in order with mixing. After a cleargel formed, Phase C was added, followed by Phase D with stirring

Maintain the agitation until homogeneous.

The following results in the Hair Styling Gel were observed:

Pearlescent pigment Result Example 7 shimmering red gold shade a brightbottle appearance with red, violet and gold iridescent sparkling effect,depending on the viewing angle Example 70 intense shimmering blackbottle appearance with red, gold green to turquoise iridescent sparklingeffect, depending on the viewing angle

Example 66 Magnetic Pearlescent Pigment

SunPearl Bronze (20 g, C84-6281, SunChemical) was reduced as describedin Example 8 to form a deep and intensely colored, golden-beigepearlescent pigment (seen Table 7 for corresponding CIELAB color values)was obtained. The magnetic susceptibility of the resulting pigment aswell as, the starting pigment were measured by Applied Paleomagnetics inSanta Cruz, Calif. using a Bartington MS2 susceptibility meter.

TABLE 26 Magnetic susceptibility of Example 66. Magnetic Susceptibility× 10⁵ Sample Color (m³/kg) SunPearl Bronze Bronze 0.019 Example 66Golden-Beige 5.056

Example 67 Particle Alignment of Example 66 Using a Magnetic Field

Pigment drawdowns of the pigment prepared in Example 66 and the startingpigment of SunPearl Bronze were prepared as described in Example 32.

Four circular button magnets (13 mm ProMAG®, Magnetic Specialty LLC,Neodymium (Grade 35, 12,300 gauss) magnet) were placed on a tray in anoven maintained at 50° C. After positioning the magnets, a 0.64 cm thickglass plate was placed directly over the magnets. Directly followingapplication of the pigment suspensions, the opacity card is placed onthe glass plate so that each circular magnet is located directly beneaththe white and black background for both the starting pigment of Example66 and the pigment prepared in Example 66. The pigment prepared inExample 66 (magnetic susceptibility=5.056×10⁻⁵ m³/kg) instantaneouslyoriented into a three-dimensional circular pattern with unique depth ofperception above both the white and black background. The startingmaterial from Example 66, SunPearl Bronze (magneticsusceptibility=0.019×10⁻⁵ m³m/kg), displayed no change upon placementabove the magnetic field, indicating that the mass susceptibility wastoo low to orient the pigment in this magnetic field. After 10-15minutes in the oven, the three-dimensional image was cured and fixedwithin the coating.

The CIELAB values of the coatings were measured as described in Example32. The aligned pigment, was measured in the center of the circularimage formed by the magnet. The central portion of three-dimensionalmagnetic image appears black (L*˜30) over both the white and blackbackgrounds. The black appearance may be due to the orientation of theplatelet-like pigments normal to the surface. Alignment normal to thesurface significantly reduces the area available for reflectionresulting in a black appearance. The measured color difference (ΔE*)between the central portion of the circular image (maximum alignmentnormal to the coating surface) and the region devoid of the appliedmagnetic field was 25.9 and 27.2 over white and black respectively, asshown in Table 27.

TABLE 27 CIELAB Color of Magnetically Aligned Pigments Dry WhiteBackground Black Background Pigment L* a b Hue L* a b Hue Example Colorvalue value value Chroma Angle value value value Chroma Angle SunPearlBronze 63.51 18.61 28.33 33.9 56.70 63.1 17.09 27.78 32.61 58.39 BronzeUnaligned Golden- 54.27 6.4 15.84 17.08 68.01 54.30 6.33 15.73 16.9668.07 Example 66 Beige Central Portion Not 30.78 4.22 5.03 6.57 50.0129.99 2.79 4.08 4.94 55.61 of 3-D Circular Applicable Image in Example66

Example 68 Magnetic Properties of Green Pearlescent Pigment

A pearlescent pigment is prepared as described in Example 25, forming aneon-like lustrous pigment having a green interference color combinedwith a golden yellow absorbance color (Example 68a). The pigment wasthen reduced using the procedure described in Example 27 to form anopaque olive green, lustrous pearlescent pigment (Example 68b). Themagnetic susceptibility of the pigments measured before and afterhydrogenation is given in Table 28. As shown, the magneticsusceptibility increased by roughly three orders of magnitude followinghydrogenation.

TABLE 28 Magnetic susceptibility of Example 68. Magnetic Mass DryPigment Susceptibility × 10⁻⁵ Sample Color (m³/kg) Example 68a NeonGreen- 0.008 (Before Reduction) Gold Example 68b (After Olive 7.165Reduction)

Pigment drawdowns for both pigments were made and measured as describedin Example 67. The measured color difference (ΔE*) between the centralportion of the circular image (maximum alignment normal to the coatingsurface) and the region devoid of the applied magnetic field was 24.1and 28.3 over white and black respectively.

TABLE 29 CIELAB Color of Magnetically Aligned Pigments Dry WhiteBackground Black Background Pigment L* a b Hue L* b Hue Example Colorvalue value value Chroma Angle value a value value Chroma Angle Example68a Neon 74.61 7.98 43.64 44.36 79.64 61.27 −10.78 26.16 28.3 112.4(Before Green- Reduction) Gold Example 68b Olive 49.64 −5.58 18.52 19.35106.77 48.18 −7.3 16.93 18.44 113.33 (After Reduction) Central PortionNot 30.83 2.66 5.84 6.42 65.52 26.2 −0.37 0.48 0.61 127.36 of 3-DCircular Applicable Image in Example 4b

Example 69 Magnetic Properties of a Blue Pearlescent Pigment

A pearlescent pigment is prepared as described in Example 23, forming asemi-opaque lustrous blue pearlescent pigment with a magnetic masssusceptibility of 3.858×10⁻⁵ m³/kg.

Pigment drawdowns for the pigment was made and measured as described inExample 67, and shown in Table 30. The measured color difference (ΔE*)between the central portion of the circular image (maximum alignmentnormal to the coating surface) and the region devoid of the appliedmagnetic field was 21.43 and 21.33 over white and black respectively.

TABLE 30 CIELAB Color of Magnetically Aligned Pigments Dry WhiteBackground Black Background Pigment L* a b Hue L* b Hue Example Colorvalue value value Chroma Angle value a value value Chroma Angle Example69 Blue 45.18 −5.74 −3.59 6.77 212.00 43.32 −10.30 −6.48 12.17 212.16(After Reduction) Central Portion Not 32.65 7.71 7.42 10.70 43.91 25.800.33 −0.58 0.67 299.54 of 3-D Circular Applicable Image in Example 69

Example 70 Preparation of a Magnetic Black Pearlescent Pigment

A pearlescent pigment is prepared as described in Example 68, exceptthat SunPearl Maroon is used. The pigment was then reduced using theprocedure described in Example 8 to form an opaque onyx blackpearlescent pigment with a magnetic mass susceptibility of 14.017×10⁻⁵m³/kg.

Pigment drawdowns for the pigment was made and measured as described inExample 67, and shown in Table 31. The measured color difference (ΔE*)between the central portion of the circular image (maximum alignmentnormal to the coating surface) and the region devoid of the appliedmagnetic field was 4.2 and 5.0 over white and black respectively.

TABLE 31 CIELAB Color of Magnetically Aligned Pigments Dry WhiteBackground Black Background Pigment L* a b Hue L* b Hue Example Colorvalue value value Chroma Angle value a value value Chroma Angle Example70 Black 29.37 1.15 −2.22 2.50 297.35 29.43 1.07 −2.32 2.56 294.65Central Portion Not 25.61 0.68 −0.33 0.76 334.01 24.70 0.35 −0.80 0.88293.53 of 3-D Circular Applicable Image in Example 70

Example 71 Pearlescent Pigment in PVC

A PVC base of clear plasticol (Geon 121A, 55 parts by weight),diisodecyl phthalate plasticizer (44 parts by weight), and Mark 4152Stabilizer (1 part by weight) were mixed until uniform. The pigment ofExample 66 (1 wt % of the PVC base) was mixed with the PVC base. Theuncured polymer was drawn down on a glass plate (thickness=0.32 cm)using a 6 mil Bird applicator. The glass plate was then placed on 8circular magnets in an oven heated at 180° C. After 5 minutes, theplasticized PVC drawdown is removed from the oven and allowed to cool.The resulting plastic film has a warm beige pearlescent appearancecontaining three dimensional circular images with unique depth.

Example 72 Cosmetic Nail Enamel Use Application

The pigment from Example 66 was added at 4 wt % to a nail enamel base(Tevco, Product 8711) and mixed at 3000 rpm for 3 minutes using aDAC150FVZ-K model (Hauschild Engineering) high speed mixer. The nailenamel was then applied to an opacity card (Leneta Form 3B) using a 3mil (˜76 micron) Bird applicator.

Four circular button magnets (13 mm ProMAG®, Magnetic Specialty LLC)were placed on a tray in an oven maintained at 50° C. After positioningthe magnets, a 0.64 cm thick glass plate was placed directly over themagnets. Directly following application of the nail enamel, the opacitycard is placed on the glass plate such that two circular magnets arelocated directly beneath both the white and black background.

Upon placement of the card, the pigment prepared in Example 66instantaneously oriented into a three-dimensional circular pattern withunique depth of perception above both the white and black background.

Comparative Example 73 Acrylic Enamel Coatings of Commercially AvailableProducts

Commercially available colored pearlescent pigments were tested, fortheir magnetic mass susceptibility, and CIELAB color for aligned andnon-aligned pigments in coatings.

TABLE 32 Mass susceptibility and composition. Mass Susceptibility ×Sample Supplier Composition 10⁵ (m³/kg) Cloisonné ® Nu BASF Mica, TiO₂,Fe₃O₄,  7.966 Antique Gold Fe₃O₂ Colorona Merck Mica and Iron 11.556Blackstar ® Red Oxides (CI: 77499) Colorona Merck Mica and Iron Notavailable Blackstar ® Blue Oxides (CI: 77499) Colorona Merck Mica andIron 11.084 Blackstar ® Gold Oxides (CI: 77499) Colorona Merck Mica andIron Not available Blackstar ® Oxides (CI: 77499) Green

The drawdown procedure used in Example 67 was applied to the pigmentslisted in Table 32. The application of the magnetic field to theCloisonné® Nu Antique Gold pigment did not show the dramatic plateletrealignment to create the three-dimensional effect, instead the coatingwas only darkened. The pigment may be made from magnetic iron oxideparticles that are not bound to the platelet substrate. Consequently,application of a magnetic field does not align the platelets to give thethree-dimensional effect. The CIELAB values of the other coatings weremeasured as described in Example 67.

TABLE 33 CIELAB Color of Magnetically Aligned Pigments Dry WhiteBackground Black Background Pigment L* a b Hue L* b Hue Example Colorvalue value value Chroma Angle value a value value Chroma Angle ColoronaBlack-Red 34.50 9.73 2.14 9.97 12.42 34.63 9.65 1.88 9.84 11.05Blackstar ® Red (or CBR) Central Portion Not 27.01 2.54 0.96 2.71 20.7125.76 1.58 0.04 1.58 1.62 of 3-D Circular Applicable Image in CBRColorona Black-Blue 31.72 −1.52 −5.13 5.35 253.48 31.88 −1.78 −5.39 5.67251.76 Blackstar ® Blue (or CBB) Central Portion Not 29.86 −0.77 −4.114.18 259.34 30.42 −1.31 −4.85 5.03 254.92 of 3-D Circular ApplicableImage in CBB Colorona Black-Gold 44.70 9.91 18.55 21.04 61.89 45.1710.00 18.88 21.36 62.09 Blackstar ® Gold (or CBG) Central Portion Not30.56 4.93 6.27 7.97 51.80 29.99 3.89 5.42 6.67 54.33 of 3-D CircularApplicable Image in CBG Colorona Black- 33.66 −4.17 −2.29 4.76 208.7533.9 −4.39 −2.31 4.96 207.77 Blackstar ® Green Green (or CBGr) CentralPortion Not 25.49 0.09 −1.12 1.13 274.74 25.51 −0.14 −1.28 1.29 263.59of 3-D Circular Applicable Image in CBGr

Table 34 shows the measured color difference (ΔE*) between themagnetically aligned region and the region devoid of the magnetic fieldof the examples is higher than the color difference for commerciallyavailable pigments.

TABLE 34 The change in color difference (ΔE*) between the region devoidof the applied external magnetic field and the center portion of thealigned 3-D circular image. White Black Dry Pigment Background,Background, Example Color ΔE* ΔE* Example 66 Golden-Beige 25.94 27.19Example 68 Olive Green 24.14 28.31 Example 69 Blue 21.43 21.33 ColoronaBlack-Red 10.45 12.13 Blackstar ® Red Colorona Black-Blue 2.25 1.62Blackstar ® Blue Colorona Black-Gold 19.38 21.19 Blackstar ® GoldColorona Black-Green 9.29 9.46 Blackstar ® Green

1. A process for making a pearlescent pigment, comprising reducing ametal oxide coated substrate with a hydrogen source in the presence of anoble metal catalyst in a liquid medium.
 2. The process of claim 1wherein the substrate is coated with a metal oxide by precipitating themetal from a solution in the presence of a base, before the reductionprocess.
 3. The process of claim 1, wherein the pressure of thereduction is above atmospheric pressure.
 4. The process of claim 1,wherein the concentration of noble metal catalyst is about 0.001 toabout 0.2 g of noble metal catalyst per kilogram of liquid medium. 5.The process of claim 1, wherein the concentration of noble metalcatalyst is about 0.01 to about 0.08 g of noble metal catalyst perkilogram of liquid medium.
 6. The process of claim 1, wherein the noblemetal catalyst comprises a metal selected from the group consisting ofPt, Pd, Rh, Au, Ag and Ta.
 7. The process of claim 1, wherein the noblemetal catalyst comprises Pt.
 8. The process of claim 1, wherein thesubstrate comprises natural or synthetic mica.
 9. The process of claim1, wherein the substrate comprises natural or synthetic mica coated withTiO₂ or Fe₂O₃.
 10. The process of claim 1, wherein the catalystparticulate is submicron in size.
 11. The process of claim 1, whereinthe catalyst comprises a nanoparticulate.
 12. The process of claim 11,wherein a colloidal suspension comprises the catalyst.
 13. The processof claim 12, wherein the colloidal suspension comprises Pt and apolyvinylpyrrolidone polymer.
 14. The process of claim 1, wherein themetal oxide is Fe₂O₃.
 15. The process of claim 14, wherein from about 1%to about 30% of the Fe(III) is reduced to Fe(II).
 16. A process formaking a pearlescent pigment, comprising reducing an iron oxide coatedsubstrate with a hydrogen source, wherein only about 1% to about 30% ofthe iron is reduced.
 17. The process of claim 16, wherein the reductionis in the presence of a noble metal catalyst.
 18. The process of claim17, wherein the noble metal catalyst comprises a metal selected from thegroup consisting of Pt, Pd, Rh, Au, Ag and Ta.
 19. The process of claim16, wherein the iron oxide is Fe₂O₃, and the reduced iron oxide is FeO.20. A pearlescent pigment comprising a substrate and a first layer,wherein the first layer comprises iron oxide, wherein the iron of theiron oxide has from about 1% to about 30% Fe(II) and from about 70% toabout 99% Fe(III).
 21. The pearlescent pigment of claim 20, wherein theiron of the iron oxide, is about 1% to about 15% of the weight of thepigment.
 22. The pearlescent pigment of claim 20, wherein the meanthickness of the iron oxide layer is about 10 nm to about 350 nm. 23.The pearlescent pigment of claim 20, wherein the substrate is selectedfrom the group consisting of natural mica, synthetic mica, glass flakes,Al₂O₃ platelets, SiO₂ platelets, BiOCl, borosilicate, synthetic alumina,and boron nitride.
 24. The pearlescent pigment of claim 23, wherein thepearlescent pigment further comprises a second layer located between thesubstrate and the first layer, wherein the second layer comprises anoxide selected from the group consisting of TiO₂, Fe₂O₃, ZrO₂, SnO₂,Cr₂O₃, BiOCl, and ZnO.